├── .gitattributes
├── .github
    └── workflows
    │   └── build.yml
├── .gitignore
├── .npmrc
├── LICENSE
├── README.md
├── index.html
├── package.json
└── spec.emu


/.gitattributes:
--------------------------------------------------------------------------------
1 | index.html  -diff merge=ours
2 | spec.js     -diff merge=ours
3 | spec.css    -diff merge=ours
4 | 


--------------------------------------------------------------------------------
/.github/workflows/build.yml:
--------------------------------------------------------------------------------
 1 | name: Deploy spec
 2 | 
 3 | on: [push]
 4 | 
 5 | jobs:
 6 |   build:
 7 |     runs-on: ubuntu-latest
 8 | 
 9 |     steps:
10 |     - uses: actions/checkout@v2
11 |     - uses: actions/setup-node@v1
12 |       with:
13 |         node-version: '12.x'
14 |     - run: npm install
15 |     - run: npm run build
16 |     - name: commit changes
17 |       uses: elstudio/actions-js-build/commit@v3
18 |       with:
19 |         commitMessage: "fixup: [spec] `npm run build`"
20 | 


--------------------------------------------------------------------------------
/.gitignore:
--------------------------------------------------------------------------------
 1 | # Logs
 2 | logs
 3 | *.log
 4 | npm-debug.log*
 5 | 
 6 | # Runtime data
 7 | pids
 8 | *.pid
 9 | *.seed
10 | 
11 | # Directory for instrumented libs generated by jscoverage/JSCover
12 | lib-cov
13 | 
14 | # Coverage directory used by tools like istanbul
15 | coverage
16 | 
17 | # nyc test coverage
18 | .nyc_output
19 | 
20 | # Grunt intermediate storage (http://gruntjs.com/creating-plugins#storing-task-files)
21 | .grunt
22 | 
23 | # node-waf configuration
24 | .lock-wscript
25 | 
26 | # Compiled binary addons (http://nodejs.org/api/addons.html)
27 | build/Release
28 | 
29 | # Dependency directories
30 | node_modules
31 | jspm_packages
32 | 
33 | # Optional npm cache directory
34 | .npm
35 | 
36 | # Optional REPL history
37 | .node_repl_history
38 | 
39 | # Only apps should have lockfiles
40 | yarn.lock
41 | package-lock.json
42 | npm-shrinkwrap.json
43 | pnpm-lock.yaml
44 | 


--------------------------------------------------------------------------------
/.npmrc:
--------------------------------------------------------------------------------
1 | package-lock=false
2 | 


--------------------------------------------------------------------------------
/LICENSE:
--------------------------------------------------------------------------------
 1 | MIT License
 2 | 
 3 | Copyright (c) 2021 ECMA TC39 and contributors
 4 | 
 5 | Permission is hereby granted, free of charge, to any person obtaining a copy
 6 | of this software and associated documentation files (the "Software"), to deal
 7 | in the Software without restriction, including without limitation the rights
 8 | to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 9 | copies of the Software, and to permit persons to whom the Software is
10 | furnished to do so, subject to the following conditions:
11 | 
12 | The above copyright notice and this permission notice shall be included in all
13 | copies or substantial portions of the Software.
14 | 
15 | THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 | IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 | FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
18 | AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 | LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
20 | OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
21 | SOFTWARE.
22 | 


--------------------------------------------------------------------------------
/README.md:
--------------------------------------------------------------------------------
 1 | # Proposal-array-grouping.
 2 | 
 3 | 
 4 | 
 5 | A proposal to make grouping of items in an array easier.
 6 | 
 7 | ```js
 8 | const array = [1, 2, 3, 4, 5];
 9 | 
10 | // groupBy groups items by arbitrary key.
11 | // In this case, we're grouping by even/odd keys
12 | array.groupBy(i => {
13 |   return i % 2 === 0 ? 'even': 'odd';
14 | });
15 | 
16 | // =>  { odd: [1, 3, 5], even: [2, 4] }
17 | ```
18 | 
19 | ## Champions
20 | 
21 | - Justin Ridgewell ([@jridgewell](https://github.com/jridgewell/))
22 | 
23 | ## Status
24 | 
25 | Current [Stage](https://tc39.es/process-document/): 2
26 | 
27 | ## Motivation
28 | 
29 | TODO
30 | 
31 | ## Polyfill
32 | 
33 | - A polyfill is available in the [core-js](https://github.com/zloirock/core-js) library. You can find it in the [ECMAScript proposals section](https://github.com/zloirock/core-js#array-grouping).
34 | 
35 | ## Related
36 | 
37 | - Lodash
38 |   - [`_.groupBy`](https://lodash.com/docs/4.17.15#groupBy) ([850k downloads/week](https://www.npmjs.com/package/lodash.groupby))
39 | 
40 | [![Typing SVG](https://readme-typing-svg.herokuapp.com?color=%2318f9ee&size=22&lines=Thanks+for+visiting)](https://git.io/typing-svg)
41 | 


--------------------------------------------------------------------------------
/index.html:
--------------------------------------------------------------------------------
   1 | <!doctype html>
   2 | <head><meta charset="utf-8">
   3 | <link rel="stylesheet" href="./spec.css">
   4 | <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/highlight.js/8.4/styles/github.min.css">
   5 | <script src="./spec.js"></script>
   6 | <title>Array Grouping</title><script>'use strict';
   7 | let sdoBox = {
   8 |   init() {
   9 |     this.$alternativeId = null;
  10 |     this.$outer = document.createElement('div');
  11 |     this.$outer.classList.add('toolbox-container');
  12 |     this.$container = document.createElement('div');
  13 |     this.$container.classList.add('toolbox');
  14 |     this.$displayLink = document.createElement('a');
  15 |     this.$displayLink.setAttribute('href', '#');
  16 |     this.$displayLink.textContent = 'Syntax-Directed Operations';
  17 |     this.$displayLink.addEventListener('click', e => {
  18 |       e.preventDefault();
  19 |       e.stopPropagation();
  20 |       referencePane.showSDOs(sdoMap[this.$alternativeId] || {}, this.$alternativeId);
  21 |     });
  22 |     this.$container.appendChild(this.$displayLink);
  23 |     this.$outer.appendChild(this.$container);
  24 |     document.body.appendChild(this.$outer);
  25 |   },
  26 | 
  27 |   activate(el) {
  28 |     clearTimeout(this.deactiveTimeout);
  29 |     Toolbox.deactivate();
  30 |     this.$alternativeId = el.id;
  31 |     let numSdos = Object.keys(sdoMap[this.$alternativeId] || {}).length;
  32 |     this.$displayLink.textContent = 'Syntax-Directed Operations (' + numSdos + ')';
  33 |     this.$outer.classList.add('active');
  34 |     let top = el.offsetTop - this.$outer.offsetHeight;
  35 |     let left = el.offsetLeft + 50 - 10; // 50px = padding-left(=75px) + text-indent(=-25px)
  36 |     this.$outer.setAttribute('style', 'left: ' + left + 'px; top: ' + top + 'px');
  37 |     if (top < document.body.scrollTop) {
  38 |       this.$container.scrollIntoView();
  39 |     }
  40 |   },
  41 | 
  42 |   deactivate() {
  43 |     clearTimeout(this.deactiveTimeout);
  44 |     this.$outer.classList.remove('active');
  45 |   },
  46 | };
  47 | 
  48 | document.addEventListener('DOMContentLoaded', () => {
  49 |   if (typeof sdoMap == 'undefined') {
  50 |     console.error('could not find sdo map');
  51 |     return;
  52 |   }
  53 |   sdoBox.init();
  54 | 
  55 |   let insideTooltip = false;
  56 |   sdoBox.$outer.addEventListener('pointerenter', () => {
  57 |     insideTooltip = true;
  58 |   });
  59 |   sdoBox.$outer.addEventListener('pointerleave', () => {
  60 |     insideTooltip = false;
  61 |     sdoBox.deactivate();
  62 |   });
  63 | 
  64 |   sdoBox.deactiveTimeout = null;
  65 |   [].forEach.call(document.querySelectorAll('emu-grammar[type=definition] emu-rhs'), node => {
  66 |     node.addEventListener('pointerenter', function () {
  67 |       sdoBox.activate(this);
  68 |     });
  69 | 
  70 |     node.addEventListener('pointerleave', () => {
  71 |       sdoBox.deactiveTimeout = setTimeout(() => {
  72 |         if (!insideTooltip) {
  73 |           sdoBox.deactivate();
  74 |         }
  75 |       }, 500);
  76 |     });
  77 |   });
  78 | 
  79 |   document.addEventListener(
  80 |     'keydown',
  81 |     debounce(e => {
  82 |       if (e.code === 'Escape') {
  83 |         sdoBox.deactivate();
  84 |       }
  85 |     })
  86 |   );
  87 | });
  88 | 
  89 | 'use strict';
  90 | function Search(menu) {
  91 |   this.menu = menu;
  92 |   this.$search = document.getElementById('menu-search');
  93 |   this.$searchBox = document.getElementById('menu-search-box');
  94 |   this.$searchResults = document.getElementById('menu-search-results');
  95 | 
  96 |   this.loadBiblio();
  97 | 
  98 |   document.addEventListener('keydown', this.documentKeydown.bind(this));
  99 | 
 100 |   this.$searchBox.addEventListener(
 101 |     'keydown',
 102 |     debounce(this.searchBoxKeydown.bind(this), { stopPropagation: true })
 103 |   );
 104 |   this.$searchBox.addEventListener(
 105 |     'keyup',
 106 |     debounce(this.searchBoxKeyup.bind(this), { stopPropagation: true })
 107 |   );
 108 | 
 109 |   // Perform an initial search if the box is not empty.
 110 |   if (this.$searchBox.value) {
 111 |     this.search(this.$searchBox.value);
 112 |   }
 113 | }
 114 | 
 115 | Search.prototype.loadBiblio = function () {
 116 |   if (typeof biblio === 'undefined') {
 117 |     console.error('could not find biblio');
 118 |     this.biblio = { refToClause: {}, entries: [] };
 119 |   } else {
 120 |     this.biblio = biblio;
 121 |     this.biblio.clauses = this.biblio.entries.filter(e => e.type === 'clause');
 122 |     this.biblio.byId = this.biblio.entries.reduce((map, entry) => {
 123 |       map[entry.id] = entry;
 124 |       return map;
 125 |     }, {});
 126 |     let refParentClause = Object.create(null);
 127 |     this.biblio.refParentClause = refParentClause;
 128 |     let refsByClause = this.biblio.refsByClause;
 129 |     Object.keys(refsByClause).forEach(clause => {
 130 |       refsByClause[clause].forEach(ref => {
 131 |         refParentClause[ref] = clause;
 132 |       });
 133 |     });
 134 |   }
 135 | };
 136 | 
 137 | Search.prototype.documentKeydown = function (e) {
 138 |   if (e.keyCode === 191) {
 139 |     e.preventDefault();
 140 |     e.stopPropagation();
 141 |     this.triggerSearch();
 142 |   }
 143 | };
 144 | 
 145 | Search.prototype.searchBoxKeydown = function (e) {
 146 |   e.stopPropagation();
 147 |   e.preventDefault();
 148 |   if (e.keyCode === 191 && e.target.value.length === 0) {
 149 |     e.preventDefault();
 150 |   } else if (e.keyCode === 13) {
 151 |     e.preventDefault();
 152 |     this.selectResult();
 153 |   }
 154 | };
 155 | 
 156 | Search.prototype.searchBoxKeyup = function (e) {
 157 |   if (e.keyCode === 13 || e.keyCode === 9) {
 158 |     return;
 159 |   }
 160 | 
 161 |   this.search(e.target.value);
 162 | };
 163 | 
 164 | Search.prototype.triggerSearch = function () {
 165 |   if (this.menu.isVisible()) {
 166 |     this._closeAfterSearch = false;
 167 |   } else {
 168 |     this._closeAfterSearch = true;
 169 |     this.menu.show();
 170 |   }
 171 | 
 172 |   this.$searchBox.focus();
 173 |   this.$searchBox.select();
 174 | };
 175 | // bit 12 - Set if the result starts with searchString
 176 | // bits 8-11: 8 - number of chunks multiplied by 2 if cases match, otherwise 1.
 177 | // bits 1-7: 127 - length of the entry
 178 | // General scheme: prefer case sensitive matches with fewer chunks, and otherwise
 179 | // prefer shorter matches.
 180 | function relevance(result) {
 181 |   let relevance = 0;
 182 | 
 183 |   relevance = Math.max(0, 8 - result.match.chunks) << 7;
 184 | 
 185 |   if (result.match.caseMatch) {
 186 |     relevance *= 2;
 187 |   }
 188 | 
 189 |   if (result.match.prefix) {
 190 |     relevance += 2048;
 191 |   }
 192 | 
 193 |   relevance += Math.max(0, 255 - result.entry.key.length);
 194 | 
 195 |   return relevance;
 196 | }
 197 | 
 198 | Search.prototype.search = function (searchString) {
 199 |   if (searchString === '') {
 200 |     this.displayResults([]);
 201 |     this.hideSearch();
 202 |     return;
 203 |   } else {
 204 |     this.showSearch();
 205 |   }
 206 | 
 207 |   if (searchString.length === 1) {
 208 |     this.displayResults([]);
 209 |     return;
 210 |   }
 211 | 
 212 |   let results;
 213 | 
 214 |   if (/^[\d.]*$/.test(searchString)) {
 215 |     results = this.biblio.clauses
 216 |       .filter(clause => clause.number.substring(0, searchString.length) === searchString)
 217 |       .map(clause => ({ entry: clause }));
 218 |   } else {
 219 |     results = [];
 220 | 
 221 |     for (let i = 0; i < this.biblio.entries.length; i++) {
 222 |       let entry = this.biblio.entries[i];
 223 |       if (!entry.key) {
 224 |         // biblio entries without a key aren't searchable
 225 |         continue;
 226 |       }
 227 | 
 228 |       let match = fuzzysearch(searchString, entry.key);
 229 |       if (match) {
 230 |         results.push({ entry, match });
 231 |       }
 232 |     }
 233 | 
 234 |     results.forEach(result => {
 235 |       result.relevance = relevance(result, searchString);
 236 |     });
 237 | 
 238 |     results = results.sort((a, b) => b.relevance - a.relevance);
 239 |   }
 240 | 
 241 |   if (results.length > 50) {
 242 |     results = results.slice(0, 50);
 243 |   }
 244 | 
 245 |   this.displayResults(results);
 246 | };
 247 | Search.prototype.hideSearch = function () {
 248 |   this.$search.classList.remove('active');
 249 | };
 250 | 
 251 | Search.prototype.showSearch = function () {
 252 |   this.$search.classList.add('active');
 253 | };
 254 | 
 255 | Search.prototype.selectResult = function () {
 256 |   let $first = this.$searchResults.querySelector('li:first-child a');
 257 | 
 258 |   if ($first) {
 259 |     document.location = $first.getAttribute('href');
 260 |   }
 261 | 
 262 |   this.$searchBox.value = '';
 263 |   this.$searchBox.blur();
 264 |   this.displayResults([]);
 265 |   this.hideSearch();
 266 | 
 267 |   if (this._closeAfterSearch) {
 268 |     this.menu.hide();
 269 |   }
 270 | };
 271 | 
 272 | Search.prototype.displayResults = function (results) {
 273 |   if (results.length > 0) {
 274 |     this.$searchResults.classList.remove('no-results');
 275 | 
 276 |     let html = '<ul>';
 277 | 
 278 |     results.forEach(result => {
 279 |       let entry = result.entry;
 280 |       let id = entry.id;
 281 |       let cssClass = '';
 282 |       let text = '';
 283 | 
 284 |       if (entry.type === 'clause') {
 285 |         let number = entry.number ? entry.number + ' ' : '';
 286 |         text = number + entry.key;
 287 |         cssClass = 'clause';
 288 |         id = entry.id;
 289 |       } else if (entry.type === 'production') {
 290 |         text = entry.key;
 291 |         cssClass = 'prod';
 292 |         id = entry.id;
 293 |       } else if (entry.type === 'op') {
 294 |         text = entry.key;
 295 |         cssClass = 'op';
 296 |         id = entry.id || entry.refId;
 297 |       } else if (entry.type === 'term') {
 298 |         text = entry.key;
 299 |         cssClass = 'term';
 300 |         id = entry.id || entry.refId;
 301 |       }
 302 | 
 303 |       if (text) {
 304 |         // prettier-ignore
 305 |         html += `<li class=menu-search-result-${cssClass}><a href="${makeLinkToId(id)}">${text}</a></li>`;
 306 |       }
 307 |     });
 308 | 
 309 |     html += '</ul>';
 310 | 
 311 |     this.$searchResults.innerHTML = html;
 312 |   } else {
 313 |     this.$searchResults.innerHTML = '';
 314 |     this.$searchResults.classList.add('no-results');
 315 |   }
 316 | };
 317 | 
 318 | function Menu() {
 319 |   this.$toggle = document.getElementById('menu-toggle');
 320 |   this.$menu = document.getElementById('menu');
 321 |   this.$toc = document.querySelector('menu-toc > ol');
 322 |   this.$pins = document.querySelector('#menu-pins');
 323 |   this.$pinList = document.getElementById('menu-pins-list');
 324 |   this.$toc = document.querySelector('#menu-toc > ol');
 325 |   this.$specContainer = document.getElementById('spec-container');
 326 |   this.search = new Search(this);
 327 | 
 328 |   this._pinnedIds = {};
 329 |   this.loadPinEntries();
 330 | 
 331 |   // toggle menu
 332 |   this.$toggle.addEventListener('click', this.toggle.bind(this));
 333 | 
 334 |   // keydown events for pinned clauses
 335 |   document.addEventListener('keydown', this.documentKeydown.bind(this));
 336 | 
 337 |   // toc expansion
 338 |   let tocItems = this.$menu.querySelectorAll('#menu-toc li');
 339 |   for (let i = 0; i < tocItems.length; i++) {
 340 |     let $item = tocItems[i];
 341 |     $item.addEventListener('click', event => {
 342 |       $item.classList.toggle('active');
 343 |       event.stopPropagation();
 344 |     });
 345 |   }
 346 | 
 347 |   // close toc on toc item selection
 348 |   let tocLinks = this.$menu.querySelectorAll('#menu-toc li > a');
 349 |   for (let i = 0; i < tocLinks.length; i++) {
 350 |     let $link = tocLinks[i];
 351 |     $link.addEventListener('click', event => {
 352 |       this.toggle();
 353 |       event.stopPropagation();
 354 |     });
 355 |   }
 356 | 
 357 |   // update active clause on scroll
 358 |   window.addEventListener('scroll', debounce(this.updateActiveClause.bind(this)));
 359 |   this.updateActiveClause();
 360 | 
 361 |   // prevent menu scrolling from scrolling the body
 362 |   this.$toc.addEventListener('wheel', e => {
 363 |     let target = e.currentTarget;
 364 |     let offTop = e.deltaY < 0 && target.scrollTop === 0;
 365 |     if (offTop) {
 366 |       e.preventDefault();
 367 |     }
 368 |     let offBottom = e.deltaY > 0 && target.offsetHeight + target.scrollTop >= target.scrollHeight;
 369 | 
 370 |     if (offBottom) {
 371 |       e.preventDefault();
 372 |     }
 373 |   });
 374 | }
 375 | 
 376 | Menu.prototype.documentKeydown = function (e) {
 377 |   e.stopPropagation();
 378 |   if (e.keyCode === 80) {
 379 |     this.togglePinEntry();
 380 |   } else if (e.keyCode > 48 && e.keyCode < 58) {
 381 |     this.selectPin(e.keyCode - 49);
 382 |   }
 383 | };
 384 | 
 385 | Menu.prototype.updateActiveClause = function () {
 386 |   this.setActiveClause(findActiveClause(this.$specContainer));
 387 | };
 388 | 
 389 | Menu.prototype.setActiveClause = function (clause) {
 390 |   this.$activeClause = clause;
 391 |   this.revealInToc(this.$activeClause);
 392 | };
 393 | 
 394 | Menu.prototype.revealInToc = function (path) {
 395 |   let current = this.$toc.querySelectorAll('li.revealed');
 396 |   for (let i = 0; i < current.length; i++) {
 397 |     current[i].classList.remove('revealed');
 398 |     current[i].classList.remove('revealed-leaf');
 399 |   }
 400 | 
 401 |   current = this.$toc;
 402 |   let index = 0;
 403 |   outer: while (index < path.length) {
 404 |     let children = current.children;
 405 |     for (let i = 0; i < children.length; i++) {
 406 |       if ('#' + path[index].id === children[i].children[1].hash) {
 407 |         children[i].classList.add('revealed');
 408 |         if (index === path.length - 1) {
 409 |           children[i].classList.add('revealed-leaf');
 410 |           let rect = children[i].getBoundingClientRect();
 411 |           // this.$toc.getBoundingClientRect().top;
 412 |           let tocRect = this.$toc.getBoundingClientRect();
 413 |           if (rect.top + 10 > tocRect.bottom) {
 414 |             this.$toc.scrollTop =
 415 |               this.$toc.scrollTop + (rect.top - tocRect.bottom) + (rect.bottom - rect.top);
 416 |           } else if (rect.top < tocRect.top) {
 417 |             this.$toc.scrollTop = this.$toc.scrollTop - (tocRect.top - rect.top);
 418 |           }
 419 |         }
 420 |         current = children[i].querySelector('ol');
 421 |         index++;
 422 |         continue outer;
 423 |       }
 424 |     }
 425 |     console.log('could not find location in table of contents', path);
 426 |     break;
 427 |   }
 428 | };
 429 | 
 430 | function findActiveClause(root, path) {
 431 |   let clauses = getChildClauses(root);
 432 |   path = path || [];
 433 | 
 434 |   for (let $clause of clauses) {
 435 |     let rect = $clause.getBoundingClientRect();
 436 |     let $header = $clause.querySelector('h1');
 437 |     let marginTop = Math.max(
 438 |       parseInt(getComputedStyle($clause)['margin-top']),
 439 |       parseInt(getComputedStyle($header)['margin-top'])
 440 |     );
 441 | 
 442 |     if (rect.top - marginTop <= 1 && rect.bottom > 0) {
 443 |       return findActiveClause($clause, path.concat($clause)) || path;
 444 |     }
 445 |   }
 446 | 
 447 |   return path;
 448 | }
 449 | 
 450 | function* getChildClauses(root) {
 451 |   for (let el of root.children) {
 452 |     switch (el.nodeName) {
 453 |       // descend into <emu-import>
 454 |       case 'EMU-IMPORT':
 455 |         yield* getChildClauses(el);
 456 |         break;
 457 | 
 458 |       // accept <emu-clause>, <emu-intro>, and <emu-annex>
 459 |       case 'EMU-CLAUSE':
 460 |       case 'EMU-INTRO':
 461 |       case 'EMU-ANNEX':
 462 |         yield el;
 463 |     }
 464 |   }
 465 | }
 466 | 
 467 | Menu.prototype.toggle = function () {
 468 |   this.$menu.classList.toggle('active');
 469 | };
 470 | 
 471 | Menu.prototype.show = function () {
 472 |   this.$menu.classList.add('active');
 473 | };
 474 | 
 475 | Menu.prototype.hide = function () {
 476 |   this.$menu.classList.remove('active');
 477 | };
 478 | 
 479 | Menu.prototype.isVisible = function () {
 480 |   return this.$menu.classList.contains('active');
 481 | };
 482 | 
 483 | Menu.prototype.showPins = function () {
 484 |   this.$pins.classList.add('active');
 485 | };
 486 | 
 487 | Menu.prototype.hidePins = function () {
 488 |   this.$pins.classList.remove('active');
 489 | };
 490 | 
 491 | Menu.prototype.addPinEntry = function (id) {
 492 |   let entry = this.search.biblio.byId[id];
 493 |   if (!entry) {
 494 |     // id was deleted after pin (or something) so remove it
 495 |     delete this._pinnedIds[id];
 496 |     this.persistPinEntries();
 497 |     return;
 498 |   }
 499 | 
 500 |   if (entry.type === 'clause') {
 501 |     let prefix;
 502 |     if (entry.number) {
 503 |       prefix = entry.number + ' ';
 504 |     } else {
 505 |       prefix = '';
 506 |     }
 507 |     // prettier-ignore
 508 |     this.$pinList.innerHTML += `<li><a href="${makeLinkToId(entry.id)}">${prefix}${entry.titleHTML}</a></li>`;
 509 |   } else {
 510 |     this.$pinList.innerHTML += `<li><a href="${makeLinkToId(entry.id)}">${entry.key}</a></li>`;
 511 |   }
 512 | 
 513 |   if (Object.keys(this._pinnedIds).length === 0) {
 514 |     this.showPins();
 515 |   }
 516 |   this._pinnedIds[id] = true;
 517 |   this.persistPinEntries();
 518 | };
 519 | 
 520 | Menu.prototype.removePinEntry = function (id) {
 521 |   let item = this.$pinList.querySelector(`a[href="${makeLinkToId(id)}"]`).parentNode;
 522 |   this.$pinList.removeChild(item);
 523 |   delete this._pinnedIds[id];
 524 |   if (Object.keys(this._pinnedIds).length === 0) {
 525 |     this.hidePins();
 526 |   }
 527 | 
 528 |   this.persistPinEntries();
 529 | };
 530 | 
 531 | Menu.prototype.persistPinEntries = function () {
 532 |   try {
 533 |     if (!window.localStorage) return;
 534 |   } catch (e) {
 535 |     return;
 536 |   }
 537 | 
 538 |   localStorage.pinEntries = JSON.stringify(Object.keys(this._pinnedIds));
 539 | };
 540 | 
 541 | Menu.prototype.loadPinEntries = function () {
 542 |   try {
 543 |     if (!window.localStorage) return;
 544 |   } catch (e) {
 545 |     return;
 546 |   }
 547 | 
 548 |   let pinsString = window.localStorage.pinEntries;
 549 |   if (!pinsString) return;
 550 |   let pins = JSON.parse(pinsString);
 551 |   for (let i = 0; i < pins.length; i++) {
 552 |     this.addPinEntry(pins[i]);
 553 |   }
 554 | };
 555 | 
 556 | Menu.prototype.togglePinEntry = function (id) {
 557 |   if (!id) {
 558 |     id = this.$activeClause[this.$activeClause.length - 1].id;
 559 |   }
 560 | 
 561 |   if (this._pinnedIds[id]) {
 562 |     this.removePinEntry(id);
 563 |   } else {
 564 |     this.addPinEntry(id);
 565 |   }
 566 | };
 567 | 
 568 | Menu.prototype.selectPin = function (num) {
 569 |   document.location = this.$pinList.children[num].children[0].href;
 570 | };
 571 | 
 572 | let menu;
 573 | function init() {
 574 |   menu = new Menu();
 575 |   let $container = document.getElementById('spec-container');
 576 |   $container.addEventListener(
 577 |     'mouseover',
 578 |     debounce(e => {
 579 |       Toolbox.activateIfMouseOver(e);
 580 |     })
 581 |   );
 582 |   document.addEventListener(
 583 |     'keydown',
 584 |     debounce(e => {
 585 |       if (e.code === 'Escape' && Toolbox.active) {
 586 |         Toolbox.deactivate();
 587 |       }
 588 |     })
 589 |   );
 590 | }
 591 | 
 592 | document.addEventListener('DOMContentLoaded', init);
 593 | 
 594 | function debounce(fn, opts) {
 595 |   opts = opts || {};
 596 |   let timeout;
 597 |   return function (e) {
 598 |     if (opts.stopPropagation) {
 599 |       e.stopPropagation();
 600 |     }
 601 |     let args = arguments;
 602 |     if (timeout) {
 603 |       clearTimeout(timeout);
 604 |     }
 605 |     timeout = setTimeout(() => {
 606 |       timeout = null;
 607 |       fn.apply(this, args);
 608 |     }, 150);
 609 |   };
 610 | }
 611 | 
 612 | let CLAUSE_NODES = ['EMU-CLAUSE', 'EMU-INTRO', 'EMU-ANNEX'];
 613 | function findLocalReferences($elem) {
 614 |   let name = $elem.innerHTML;
 615 |   let references = [];
 616 | 
 617 |   let parentClause = $elem.parentNode;
 618 |   while (parentClause && CLAUSE_NODES.indexOf(parentClause.nodeName) === -1) {
 619 |     parentClause = parentClause.parentNode;
 620 |   }
 621 | 
 622 |   if (!parentClause) return;
 623 | 
 624 |   let vars = parentClause.querySelectorAll('var');
 625 | 
 626 |   for (let i = 0; i < vars.length; i++) {
 627 |     let $var = vars[i];
 628 | 
 629 |     if ($var.innerHTML === name) {
 630 |       references.push($var);
 631 |     }
 632 |   }
 633 | 
 634 |   return references;
 635 | }
 636 | 
 637 | function toggleFindLocalReferences($elem) {
 638 |   let references = findLocalReferences($elem);
 639 |   if ($elem.classList.contains('referenced')) {
 640 |     references.forEach($reference => {
 641 |       $reference.classList.remove('referenced');
 642 |     });
 643 |   } else {
 644 |     references.forEach($reference => {
 645 |       $reference.classList.add('referenced');
 646 |     });
 647 |   }
 648 | }
 649 | 
 650 | function installFindLocalReferences() {
 651 |   document.addEventListener('click', e => {
 652 |     if (e.target.nodeName === 'VAR') {
 653 |       toggleFindLocalReferences(e.target);
 654 |     }
 655 |   });
 656 | }
 657 | 
 658 | document.addEventListener('DOMContentLoaded', installFindLocalReferences);
 659 | 
 660 | // The following license applies to the fuzzysearch function
 661 | // The MIT License (MIT)
 662 | // Copyright © 2015 Nicolas Bevacqua
 663 | // Copyright © 2016 Brian Terlson
 664 | // Permission is hereby granted, free of charge, to any person obtaining a copy of
 665 | // this software and associated documentation files (the "Software"), to deal in
 666 | // the Software without restriction, including without limitation the rights to
 667 | // use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
 668 | // the Software, and to permit persons to whom the Software is furnished to do so,
 669 | // subject to the following conditions:
 670 | 
 671 | // The above copyright notice and this permission notice shall be included in all
 672 | // copies or substantial portions of the Software.
 673 | 
 674 | // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 675 | // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
 676 | // FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
 677 | // COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
 678 | // IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 679 | // CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 680 | function fuzzysearch(searchString, haystack, caseInsensitive) {
 681 |   let tlen = haystack.length;
 682 |   let qlen = searchString.length;
 683 |   let chunks = 1;
 684 |   let finding = false;
 685 | 
 686 |   if (qlen > tlen) {
 687 |     return false;
 688 |   }
 689 | 
 690 |   if (qlen === tlen) {
 691 |     if (searchString === haystack) {
 692 |       return { caseMatch: true, chunks: 1, prefix: true };
 693 |     } else if (searchString.toLowerCase() === haystack.toLowerCase()) {
 694 |       return { caseMatch: false, chunks: 1, prefix: true };
 695 |     } else {
 696 |       return false;
 697 |     }
 698 |   }
 699 | 
 700 |   let j = 0;
 701 |   outer: for (let i = 0; i < qlen; i++) {
 702 |     let nch = searchString[i];
 703 |     while (j < tlen) {
 704 |       let targetChar = haystack[j++];
 705 |       if (targetChar === nch) {
 706 |         finding = true;
 707 |         continue outer;
 708 |       }
 709 |       if (finding) {
 710 |         chunks++;
 711 |         finding = false;
 712 |       }
 713 |     }
 714 | 
 715 |     if (caseInsensitive) {
 716 |       return false;
 717 |     }
 718 | 
 719 |     return fuzzysearch(searchString.toLowerCase(), haystack.toLowerCase(), true);
 720 |   }
 721 | 
 722 |   return { caseMatch: !caseInsensitive, chunks, prefix: j <= qlen };
 723 | }
 724 | 
 725 | let Toolbox = {
 726 |   init() {
 727 |     this.$outer = document.createElement('div');
 728 |     this.$outer.classList.add('toolbox-container');
 729 |     this.$container = document.createElement('div');
 730 |     this.$container.classList.add('toolbox');
 731 |     this.$outer.appendChild(this.$container);
 732 |     this.$permalink = document.createElement('a');
 733 |     this.$permalink.textContent = 'Permalink';
 734 |     this.$pinLink = document.createElement('a');
 735 |     this.$pinLink.textContent = 'Pin';
 736 |     this.$pinLink.setAttribute('href', '#');
 737 |     this.$pinLink.addEventListener('click', e => {
 738 |       e.preventDefault();
 739 |       e.stopPropagation();
 740 |       menu.togglePinEntry(this.entry.id);
 741 |     });
 742 | 
 743 |     this.$refsLink = document.createElement('a');
 744 |     this.$refsLink.setAttribute('href', '#');
 745 |     this.$refsLink.addEventListener('click', e => {
 746 |       e.preventDefault();
 747 |       e.stopPropagation();
 748 |       referencePane.showReferencesFor(this.entry);
 749 |     });
 750 |     this.$container.appendChild(this.$permalink);
 751 |     this.$container.appendChild(this.$pinLink);
 752 |     this.$container.appendChild(this.$refsLink);
 753 |     document.body.appendChild(this.$outer);
 754 |   },
 755 | 
 756 |   activate(el, entry, target) {
 757 |     if (el === this._activeEl) return;
 758 |     sdoBox.deactivate();
 759 |     this.active = true;
 760 |     this.entry = entry;
 761 |     this.$outer.classList.add('active');
 762 |     this.top = el.offsetTop - this.$outer.offsetHeight;
 763 |     this.left = el.offsetLeft - 10;
 764 |     this.$outer.setAttribute('style', 'left: ' + this.left + 'px; top: ' + this.top + 'px');
 765 |     this.updatePermalink();
 766 |     this.updateReferences();
 767 |     this._activeEl = el;
 768 |     if (this.top < document.body.scrollTop && el === target) {
 769 |       // don't scroll unless it's a small thing (< 200px)
 770 |       this.$outer.scrollIntoView();
 771 |     }
 772 |   },
 773 | 
 774 |   updatePermalink() {
 775 |     this.$permalink.setAttribute('href', makeLinkToId(this.entry.id));
 776 |   },
 777 | 
 778 |   updateReferences() {
 779 |     this.$refsLink.textContent = `References (${this.entry.referencingIds.length})`;
 780 |   },
 781 | 
 782 |   activateIfMouseOver(e) {
 783 |     let ref = this.findReferenceUnder(e.target);
 784 |     if (ref && (!this.active || e.pageY > this._activeEl.offsetTop)) {
 785 |       let entry = menu.search.biblio.byId[ref.id];
 786 |       this.activate(ref.element, entry, e.target);
 787 |     } else if (
 788 |       this.active &&
 789 |       (e.pageY < this.top || e.pageY > this._activeEl.offsetTop + this._activeEl.offsetHeight)
 790 |     ) {
 791 |       this.deactivate();
 792 |     }
 793 |   },
 794 | 
 795 |   findReferenceUnder(el) {
 796 |     while (el) {
 797 |       let parent = el.parentNode;
 798 |       if (el.nodeName === 'EMU-RHS' || el.nodeName === 'EMU-PRODUCTION') {
 799 |         return null;
 800 |       }
 801 |       if (
 802 |         el.nodeName === 'H1' &&
 803 |         parent.nodeName.match(/EMU-CLAUSE|EMU-ANNEX|EMU-INTRO/) &&
 804 |         parent.id
 805 |       ) {
 806 |         return { element: el, id: parent.id };
 807 |       } else if (el.nodeName === 'EMU-NT') {
 808 |         if (
 809 |           parent.nodeName === 'EMU-PRODUCTION' &&
 810 |           parent.id &&
 811 |           parent.id[0] !== '_' &&
 812 |           parent.firstElementChild === el
 813 |         ) {
 814 |           // return the LHS non-terminal element
 815 |           return { element: el, id: parent.id };
 816 |         }
 817 |         return null;
 818 |       } else if (
 819 |         el.nodeName.match(/EMU-(?!CLAUSE|XREF|ANNEX|INTRO)|DFN/) &&
 820 |         el.id &&
 821 |         el.id[0] !== '_'
 822 |       ) {
 823 |         if (
 824 |           el.nodeName === 'EMU-FIGURE' ||
 825 |           el.nodeName === 'EMU-TABLE' ||
 826 |           el.nodeName === 'EMU-EXAMPLE'
 827 |         ) {
 828 |           // return the figcaption element
 829 |           return { element: el.children[0].children[0], id: el.id };
 830 |         } else {
 831 |           return { element: el, id: el.id };
 832 |         }
 833 |       }
 834 |       el = parent;
 835 |     }
 836 |   },
 837 | 
 838 |   deactivate() {
 839 |     this.$outer.classList.remove('active');
 840 |     this._activeEl = null;
 841 |     this.active = false;
 842 |   },
 843 | };
 844 | 
 845 | let referencePane = {
 846 |   init() {
 847 |     this.$container = document.createElement('div');
 848 |     this.$container.setAttribute('id', 'references-pane-container');
 849 | 
 850 |     let $spacer = document.createElement('div');
 851 |     $spacer.setAttribute('id', 'references-pane-spacer');
 852 | 
 853 |     this.$pane = document.createElement('div');
 854 |     this.$pane.setAttribute('id', 'references-pane');
 855 | 
 856 |     this.$container.appendChild($spacer);
 857 |     this.$container.appendChild(this.$pane);
 858 | 
 859 |     this.$header = document.createElement('div');
 860 |     this.$header.classList.add('menu-pane-header');
 861 |     this.$headerText = document.createElement('span');
 862 |     this.$header.appendChild(this.$headerText);
 863 |     this.$headerRefId = document.createElement('a');
 864 |     this.$header.appendChild(this.$headerRefId);
 865 |     this.$closeButton = document.createElement('span');
 866 |     this.$closeButton.setAttribute('id', 'references-pane-close');
 867 |     this.$closeButton.addEventListener('click', () => {
 868 |       this.deactivate();
 869 |     });
 870 |     this.$header.appendChild(this.$closeButton);
 871 | 
 872 |     this.$pane.appendChild(this.$header);
 873 |     let tableContainer = document.createElement('div');
 874 |     tableContainer.setAttribute('id', 'references-pane-table-container');
 875 | 
 876 |     this.$table = document.createElement('table');
 877 |     this.$table.setAttribute('id', 'references-pane-table');
 878 | 
 879 |     this.$tableBody = this.$table.createTBody();
 880 | 
 881 |     tableContainer.appendChild(this.$table);
 882 |     this.$pane.appendChild(tableContainer);
 883 | 
 884 |     menu.$specContainer.appendChild(this.$container);
 885 |   },
 886 | 
 887 |   activate() {
 888 |     this.$container.classList.add('active');
 889 |   },
 890 | 
 891 |   deactivate() {
 892 |     this.$container.classList.remove('active');
 893 |     this.state = null;
 894 |   },
 895 | 
 896 |   showReferencesFor(entry) {
 897 |     this.activate();
 898 |     this.state = { type: 'ref', id: entry.id };
 899 |     this.$headerText.textContent = 'References to ';
 900 |     let newBody = document.createElement('tbody');
 901 |     let previousId;
 902 |     let previousCell;
 903 |     let dupCount = 0;
 904 |     this.$headerRefId.textContent = '#' + entry.id;
 905 |     this.$headerRefId.setAttribute('href', makeLinkToId(entry.id));
 906 |     this.$headerRefId.style.display = 'inline';
 907 |     entry.referencingIds
 908 |       .map(id => {
 909 |         let cid = menu.search.biblio.refParentClause[id];
 910 |         let clause = menu.search.biblio.byId[cid];
 911 |         if (clause == null) {
 912 |           throw new Error('could not find clause for id ' + cid);
 913 |         }
 914 |         return { id, clause };
 915 |       })
 916 |       .sort((a, b) => sortByClauseNumber(a.clause, b.clause))
 917 |       .forEach(record => {
 918 |         if (previousId === record.clause.id) {
 919 |           previousCell.innerHTML += ` (<a href="${makeLinkToId(record.id)}">${dupCount + 2}</a>)`;
 920 |           dupCount++;
 921 |         } else {
 922 |           let row = newBody.insertRow();
 923 |           let cell = row.insertCell();
 924 |           cell.innerHTML = record.clause.number;
 925 |           cell = row.insertCell();
 926 |           cell.innerHTML = `<a href="${makeLinkToId(record.id)}">${record.clause.titleHTML}</a>`;
 927 |           previousCell = cell;
 928 |           previousId = record.clause.id;
 929 |           dupCount = 0;
 930 |         }
 931 |       }, this);
 932 |     this.$table.removeChild(this.$tableBody);
 933 |     this.$tableBody = newBody;
 934 |     this.$table.appendChild(this.$tableBody);
 935 |   },
 936 | 
 937 |   showSDOs(sdos, alternativeId) {
 938 |     let rhs = document.getElementById(alternativeId);
 939 |     let parentName = rhs.parentNode.getAttribute('name');
 940 |     let colons = rhs.parentNode.querySelector('emu-geq');
 941 |     rhs = rhs.cloneNode(true);
 942 |     rhs.querySelectorAll('emu-params,emu-constraints').forEach(e => {
 943 |       e.remove();
 944 |     });
 945 |     rhs.querySelectorAll('[id]').forEach(e => {
 946 |       e.removeAttribute('id');
 947 |     });
 948 |     rhs.querySelectorAll('a').forEach(e => {
 949 |       e.parentNode.replaceChild(document.createTextNode(e.textContent), e);
 950 |     });
 951 | 
 952 |     // prettier-ignore
 953 |     this.$headerText.innerHTML = `Syntax-Directed Operations for<br><a href="${makeLinkToId(alternativeId)}" class="menu-pane-header-production"><emu-nt>${parentName}</emu-nt> ${colons.outerHTML} </a>`;
 954 |     this.$headerText.querySelector('a').append(rhs);
 955 |     this.showSDOsBody(sdos, alternativeId);
 956 |   },
 957 | 
 958 |   showSDOsBody(sdos, alternativeId) {
 959 |     this.activate();
 960 |     this.state = { type: 'sdo', id: alternativeId, html: this.$headerText.innerHTML };
 961 |     this.$headerRefId.style.display = 'none';
 962 |     let newBody = document.createElement('tbody');
 963 |     Object.keys(sdos).forEach(sdoName => {
 964 |       let pair = sdos[sdoName];
 965 |       let clause = pair.clause;
 966 |       let ids = pair.ids;
 967 |       let first = ids[0];
 968 |       let row = newBody.insertRow();
 969 |       let cell = row.insertCell();
 970 |       cell.innerHTML = clause;
 971 |       cell = row.insertCell();
 972 |       let html = '<a href="' + makeLinkToId(first) + '">' + sdoName + '</a>';
 973 |       for (let i = 1; i < ids.length; ++i) {
 974 |         html += ' (<a href="' + makeLinkToId(ids[i]) + '">' + (i + 1) + '</a>)';
 975 |       }
 976 |       cell.innerHTML = html;
 977 |     });
 978 |     this.$table.removeChild(this.$tableBody);
 979 |     this.$tableBody = newBody;
 980 |     this.$table.appendChild(this.$tableBody);
 981 |   },
 982 | };
 983 | 
 984 | function sortByClauseNumber(clause1, clause2) {
 985 |   let c1c = clause1.number.split('.');
 986 |   let c2c = clause2.number.split('.');
 987 | 
 988 |   for (let i = 0; i < c1c.length; i++) {
 989 |     if (i >= c2c.length) {
 990 |       return 1;
 991 |     }
 992 | 
 993 |     let c1 = c1c[i];
 994 |     let c2 = c2c[i];
 995 |     let c1cn = Number(c1);
 996 |     let c2cn = Number(c2);
 997 | 
 998 |     if (Number.isNaN(c1cn) && Number.isNaN(c2cn)) {
 999 |       if (c1 > c2) {
1000 |         return 1;
1001 |       } else if (c1 < c2) {
1002 |         return -1;
1003 |       }
1004 |     } else if (!Number.isNaN(c1cn) && Number.isNaN(c2cn)) {
1005 |       return -1;
1006 |     } else if (Number.isNaN(c1cn) && !Number.isNaN(c2cn)) {
1007 |       return 1;
1008 |     } else if (c1cn > c2cn) {
1009 |       return 1;
1010 |     } else if (c1cn < c2cn) {
1011 |       return -1;
1012 |     }
1013 |   }
1014 | 
1015 |   if (c1c.length === c2c.length) {
1016 |     return 0;
1017 |   }
1018 |   return -1;
1019 | }
1020 | 
1021 | function makeLinkToId(id) {
1022 |   let hash = '#' + id;
1023 |   if (typeof idToSection === 'undefined' || !idToSection[id]) {
1024 |     return hash;
1025 |   }
1026 |   let targetSec = idToSection[id];
1027 |   return (targetSec === 'index' ? './' : targetSec + '.html') + hash;
1028 | }
1029 | 
1030 | function doShortcut(e) {
1031 |   if (!(e.target instanceof HTMLElement)) {
1032 |     return;
1033 |   }
1034 |   let target = e.target;
1035 |   let name = target.nodeName.toLowerCase();
1036 |   if (name === 'textarea' || name === 'input' || name === 'select' || target.isContentEditable) {
1037 |     return;
1038 |   }
1039 |   if (e.key === 'm' && !e.altKey && !e.ctrlKey && !e.metaKey && !e.shiftKey && usesMultipage) {
1040 |     let pathParts = location.pathname.split('/');
1041 |     let hash = location.hash;
1042 |     if (pathParts[pathParts.length - 2] === 'multipage') {
1043 |       if (hash === '') {
1044 |         let sectionName = pathParts[pathParts.length - 1];
1045 |         if (sectionName.endsWith('.html')) {
1046 |           sectionName = sectionName.slice(0, -5);
1047 |         }
1048 |         if (idToSection['sec-' + sectionName] !== undefined) {
1049 |           hash = '#sec-' + sectionName;
1050 |         }
1051 |       }
1052 |       location = pathParts.slice(0, -2).join('/') + '/' + hash;
1053 |     } else {
1054 |       location = 'multipage/' + hash;
1055 |     }
1056 |   }
1057 | }
1058 | 
1059 | document.addEventListener('keypress', doShortcut);
1060 | 
1061 | document.addEventListener('DOMContentLoaded', () => {
1062 |   Toolbox.init();
1063 |   referencePane.init();
1064 | });
1065 | 
1066 | 'use strict';
1067 | let decimalBullet = Array.from({ length: 100 }, (a, i) => '' + (i + 1));
1068 | let alphaBullet = Array.from({ length: 26 }, (a, i) => String.fromCharCode('a'.charCodeAt(0) + i));
1069 | 
1070 | // prettier-ignore
1071 | let romanBullet = ['i', 'ii', 'iii', 'iv', 'v', 'vi', 'vii', 'viii', 'ix', 'x', 'xi', 'xii', 'xiii', 'xiv', 'xv', 'xvi', 'xvii', 'xviii', 'xix', 'xx', 'xxi', 'xxii', 'xxiii', 'xxiv', 'xxv'];
1072 | // prettier-ignore
1073 | let bullets = [decimalBullet, alphaBullet, romanBullet, decimalBullet, alphaBullet, romanBullet];
1074 | 
1075 | function addStepNumberText(ol, parentIndex) {
1076 |   for (let i = 0; i < ol.children.length; ++i) {
1077 |     let child = ol.children[i];
1078 |     let index = parentIndex.concat([i]);
1079 |     let applicable = bullets[Math.min(index.length - 1, 5)];
1080 |     let span = document.createElement('span');
1081 |     span.textContent = (applicable[i] || '?') + '. ';
1082 |     span.style.fontSize = '0';
1083 |     span.setAttribute('aria-hidden', 'true');
1084 |     child.prepend(span);
1085 |     let sublist = child.querySelector('ol');
1086 |     if (sublist != null) {
1087 |       addStepNumberText(sublist, index);
1088 |     }
1089 |   }
1090 | }
1091 | document.addEventListener('DOMContentLoaded', () => {
1092 |   document.querySelectorAll('emu-alg > ol').forEach(ol => {
1093 |     addStepNumberText(ol, []);
1094 |   });
1095 | });
1096 | 
1097 | let sdoMap = JSON.parse(`{}`);
1098 | let biblio = JSON.parse(`{"refsByClause":{"sec-array.prototype.groupby":["_ref_0","_ref_1","_ref_2","_ref_3","_ref_4","_ref_5","_ref_6","_ref_7","_ref_8"],"sec-array.prototype.groupbymap":["_ref_9","_ref_10","_ref_11","_ref_12","_ref_13","_ref_14","_ref_15","_ref_16"],"sec-add-value-to-keyed-group":["_ref_17"]},"entries":[{"type":"clause","id":"sec-scope","aoid":null,"titleHTML":"Scope","number":"1","referencingIds":[],"key":"Scope"},{"type":"clause","id":"sec-array.prototype.groupby","aoid":null,"titleHTML":"Array.prototype.groupBy ( <var>callbackfn</var> [ , <var>thisArg</var> ] )","number":"2.1","referencingIds":[],"key":"Array.prototype.groupBy ( callbackfn [ , thisArg ] )"},{"type":"clause","id":"sec-array.prototype.groupbymap","aoid":null,"titleHTML":"Array.prototype.groupByMap ( <var>callbackfn</var> [ , <var>thisArg</var> ] )","number":"2.2","referencingIds":[],"key":"Array.prototype.groupByMap ( callbackfn [ , thisArg ] )"},{"type":"clause","id":"sec-add-value-to-keyed-group","aoid":null,"titleHTML":"\\n      AddValueToKeyedGroup (\\n        <var>groups</var>: a List of Records that have [[Key]] and [[Elements]] fields,\\n        <var>key</var>: an ECMAScript language value,\\n        <var>value</var>: an ECMAScript language value,\\n      )\\n    ","number":"2.3","referencingIds":[],"key":"\\n      AddValueToKeyedGroup (\\n        groups: a List of Records that have [[Key]] and [[Elements]] fields,\\n        key: an ECMAScript language value,\\n        value: an ECMAScript language value,\\n      )\\n    "},{"type":"clause","id":"sec-properties-of-the-array-prototype-object","aoid":null,"titleHTML":"Properties of the Array Prototype Object (<a href=\\"https://tc39.es/ecma262/#sec-properties-of-the-array-prototype-object\\">22.1.3</a>)","number":"2","referencingIds":[],"key":"Properties of the Array Prototype Object (22.1.3)"},{"type":"clause","id":"sec-copyright-and-software-license","aoid":null,"titleHTML":"Copyright &amp; Software License","number":"A","referencingIds":[],"key":"Copyright & Software License"}]}`);
1099 | ;let usesMultipage = false</script><style>body {
1100 |   display: flex;
1101 |   font-size: 18px;
1102 |   line-height: 1.5;
1103 |   font-family: Cambria, Palatino Linotype, Palatino, Liberation Serif, serif;
1104 |   padding: 0;
1105 |   margin: 0;
1106 |   color: #111;
1107 | }
1108 | 
1109 | #spec-container {
1110 |   padding: 0 20px;
1111 |   flex-grow: 1;
1112 |   flex-basis: 66%;
1113 |   box-sizing: border-box;
1114 |   overflow: hidden;
1115 |   padding-bottom: 1em;
1116 | }
1117 | 
1118 | body.oldtoc {
1119 |   margin: 0 auto;
1120 | }
1121 | 
1122 | a {
1123 |   text-decoration: none;
1124 |   color: #206ca7;
1125 | }
1126 | 
1127 | a:visited {
1128 |   color: #206ca7;
1129 | }
1130 | 
1131 | a:hover {
1132 |   text-decoration: underline;
1133 |   color: #239dee;
1134 | }
1135 | 
1136 | code {
1137 |   font-weight: bold;
1138 |   font-family: Consolas, Monaco, monospace;
1139 |   white-space: pre;
1140 | }
1141 | 
1142 | pre code {
1143 |   font-weight: inherit;
1144 | }
1145 | 
1146 | pre code.hljs {
1147 |   background-color: #fff;
1148 |   margin: 0;
1149 |   padding: 0;
1150 | }
1151 | 
1152 | ol.toc {
1153 |   list-style: none;
1154 |   padding-left: 0;
1155 | }
1156 | 
1157 | ol.toc ol.toc {
1158 |   padding-left: 2ex;
1159 |   list-style: none;
1160 | }
1161 | 
1162 | var {
1163 |   color: #2aa198;
1164 |   transition: background-color 0.25s ease;
1165 |   cursor: pointer;
1166 | }
1167 | 
1168 | var.referenced {
1169 |   background-color: #ffff33;
1170 | }
1171 | 
1172 | emu-const {
1173 |   font-family: sans-serif;
1174 | }
1175 | 
1176 | emu-val {
1177 |   font-weight: bold;
1178 | }
1179 | 
1180 | /* depth 1 */
1181 | emu-alg ol,
1182 | /* depth 4 */
1183 | emu-alg ol ol ol ol,
1184 | emu-alg ol.nested-thrice,
1185 | emu-alg ol.nested-twice ol,
1186 | emu-alg ol.nested-once ol ol {
1187 |   list-style-type: decimal;
1188 | }
1189 | 
1190 | /* depth 2 */
1191 | emu-alg ol ol,
1192 | emu-alg ol.nested-once,
1193 | /* depth 5 */
1194 | emu-alg ol ol ol ol ol,
1195 | emu-alg ol.nested-four-times,
1196 | emu-alg ol.nested-thrice ol,
1197 | emu-alg ol.nested-twice ol ol,
1198 | emu-alg ol.nested-once ol ol ol {
1199 |   list-style-type: lower-alpha;
1200 | }
1201 | 
1202 | /* depth 3 */
1203 | emu-alg ol ol ol,
1204 | emu-alg ol.nested-twice,
1205 | emu-alg ol.nested-once ol,
1206 | /* depth 6 */
1207 | emu-alg ol ol ol ol ol ol,
1208 | emu-alg ol.nested-lots,
1209 | emu-alg ol.nested-four-times ol,
1210 | emu-alg ol.nested-thrice ol ol,
1211 | emu-alg ol.nested-twice ol ol ol,
1212 | emu-alg ol.nested-once ol ol ol ol,
1213 | /* depth 7+ */
1214 | emu-alg ol.nested-lots ol {
1215 |   list-style-type: lower-roman;
1216 | }
1217 | 
1218 | emu-eqn {
1219 |   display: block;
1220 |   margin-left: 4em;
1221 | }
1222 | 
1223 | emu-eqn.inline {
1224 |   display: inline;
1225 |   margin: 0;
1226 | }
1227 | 
1228 | emu-eqn div:first-child {
1229 |   margin-left: -2em;
1230 | }
1231 | 
1232 | emu-note {
1233 |   margin: 1em 0;
1234 |   display: flex;
1235 |   flex-direction: row;
1236 |   color: inherit;
1237 |   border-left: 5px solid #52e052;
1238 |   background: #e9fbe9;
1239 |   padding: 10px 10px 10px 0;
1240 | }
1241 | 
1242 | emu-note > span.note {
1243 |   flex-basis: 100px;
1244 |   min-width: 100px;
1245 |   flex-grow: 0;
1246 |   flex-shrink: 1;
1247 |   text-transform: uppercase;
1248 |   padding-left: 5px;
1249 | }
1250 | 
1251 | emu-note[type='editor'] {
1252 |   border-left-color: #faa;
1253 | }
1254 | 
1255 | emu-note > div.note-contents {
1256 |   flex-grow: 1;
1257 |   flex-shrink: 1;
1258 |   overflow: auto;
1259 | }
1260 | 
1261 | emu-note > div.note-contents > p:first-of-type {
1262 |   margin-top: 0;
1263 | }
1264 | 
1265 | emu-note > div.note-contents > p:last-of-type {
1266 |   margin-bottom: 0;
1267 | }
1268 | 
1269 | emu-table td code {
1270 |   white-space: normal;
1271 | }
1272 | 
1273 | emu-figure {
1274 |   display: block;
1275 | }
1276 | 
1277 | emu-example {
1278 |   display: block;
1279 |   margin: 1em 3em;
1280 | }
1281 | 
1282 | emu-example figure figcaption {
1283 |   margin-top: 0.5em;
1284 |   text-align: left;
1285 | }
1286 | 
1287 | emu-figure figure,
1288 | emu-example figure,
1289 | emu-table figure {
1290 |   display: flex;
1291 |   flex-direction: column;
1292 |   align-items: center;
1293 | }
1294 | 
1295 | emu-production {
1296 |   display: block;
1297 | }
1298 | 
1299 | emu-grammar[type='example'] emu-production,
1300 | emu-grammar[type='definition'] emu-production {
1301 |   margin-top: 1em;
1302 |   margin-bottom: 1em;
1303 |   margin-left: 5ex;
1304 | }
1305 | 
1306 | emu-grammar.inline,
1307 | emu-production.inline,
1308 | emu-grammar.inline emu-production emu-rhs,
1309 | emu-production.inline emu-rhs,
1310 | emu-grammar[collapsed] emu-production emu-rhs {
1311 |   display: inline;
1312 |   padding-left: 1ex;
1313 |   margin-left: 0;
1314 | }
1315 | 
1316 | emu-production[collapsed] emu-rhs {
1317 |   display: inline;
1318 |   padding-left: 0.5ex;
1319 |   margin-left: 0;
1320 | }
1321 | 
1322 | emu-grammar[collapsed] emu-production,
1323 | emu-production[collapsed] {
1324 |   margin: 0;
1325 | }
1326 | 
1327 | emu-constraints {
1328 |   font-size: 0.75em;
1329 |   margin-right: 0.5ex;
1330 | }
1331 | 
1332 | emu-gann {
1333 |   margin-right: 0.5ex;
1334 | }
1335 | 
1336 | emu-gann emu-t:last-child,
1337 | emu-gann emu-gprose:last-child,
1338 | emu-gann emu-nt:last-child {
1339 |   margin-right: 0;
1340 | }
1341 | 
1342 | emu-geq {
1343 |   margin-left: 0.5ex;
1344 |   font-weight: bold;
1345 | }
1346 | 
1347 | emu-oneof {
1348 |   font-weight: bold;
1349 |   margin-left: 0.5ex;
1350 | }
1351 | 
1352 | emu-nt {
1353 |   display: inline-block;
1354 |   font-style: italic;
1355 |   white-space: nowrap;
1356 |   text-indent: 0;
1357 | }
1358 | 
1359 | emu-nt a,
1360 | emu-nt a:visited {
1361 |   color: #333;
1362 | }
1363 | 
1364 | emu-rhs emu-nt {
1365 |   margin-right: 0.5ex;
1366 | }
1367 | 
1368 | emu-t {
1369 |   display: inline-block;
1370 |   font-family: monospace;
1371 |   font-weight: bold;
1372 |   white-space: nowrap;
1373 |   text-indent: 0;
1374 | }
1375 | 
1376 | emu-production emu-t {
1377 |   margin-right: 0.5ex;
1378 | }
1379 | 
1380 | emu-rhs {
1381 |   display: block;
1382 |   padding-left: 75px;
1383 |   text-indent: -25px;
1384 | }
1385 | 
1386 | emu-production:not([collapsed]) emu-rhs {
1387 |   border: 0.2ex dashed transparent;
1388 | }
1389 | 
1390 | emu-production:not([collapsed]) emu-rhs:hover {
1391 |   border-color: #888;
1392 |   background-color: #f0f0f0;
1393 | }
1394 | 
1395 | emu-mods {
1396 |   font-size: 0.85em;
1397 |   vertical-align: sub;
1398 |   font-style: normal;
1399 |   font-weight: normal;
1400 | }
1401 | 
1402 | emu-params,
1403 | emu-opt {
1404 |   margin-right: 1ex;
1405 |   font-family: monospace;
1406 | }
1407 | 
1408 | emu-params,
1409 | emu-constraints {
1410 |   color: #2aa198;
1411 | }
1412 | 
1413 | emu-opt {
1414 |   color: #b58900;
1415 | }
1416 | 
1417 | emu-gprose {
1418 |   font-size: 0.9em;
1419 |   font-family: Helvetica, Arial, sans-serif;
1420 | }
1421 | 
1422 | emu-production emu-gprose {
1423 |   margin-right: 1ex;
1424 | }
1425 | 
1426 | h1.shortname {
1427 |   color: #f60;
1428 |   font-size: 1.5em;
1429 |   margin: 0;
1430 | }
1431 | 
1432 | h1.version {
1433 |   color: #f60;
1434 |   font-size: 1.5em;
1435 | }
1436 | 
1437 | h1.title {
1438 |   color: #f60;
1439 | }
1440 | 
1441 | h1,
1442 | h2,
1443 | h3,
1444 | h4,
1445 | h5,
1446 | h6 {
1447 |   position: relative;
1448 | }
1449 | 
1450 | h1 .secnum {
1451 |   text-decoration: none;
1452 |   margin-right: 5px;
1453 | }
1454 | 
1455 | h1 span.title {
1456 |   order: 2;
1457 | }
1458 | 
1459 | h1 {
1460 |   font-size: 2.67em;
1461 |   margin-bottom: 0;
1462 |   line-height: 1em;
1463 | }
1464 | h2 {
1465 |   font-size: 2em;
1466 | }
1467 | h3 {
1468 |   font-size: 1.56em;
1469 | }
1470 | h4 {
1471 |   font-size: 1.25em;
1472 | }
1473 | h5 {
1474 |   font-size: 1.11em;
1475 | }
1476 | h6 {
1477 |   font-size: 1em;
1478 | }
1479 | 
1480 | pre code.hljs {
1481 |   background: transparent;
1482 | }
1483 | 
1484 | emu-clause[id],
1485 | emu-annex[id],
1486 | emu-intro[id] {
1487 |   scroll-margin-top: 2ex;
1488 | }
1489 | 
1490 | emu-intro h1,
1491 | emu-clause h1,
1492 | emu-annex h1 {
1493 |   font-size: 2em;
1494 | }
1495 | emu-intro h2,
1496 | emu-clause h2,
1497 | emu-annex h2 {
1498 |   font-size: 1.56em;
1499 | }
1500 | emu-intro h3,
1501 | emu-clause h3,
1502 | emu-annex h3 {
1503 |   font-size: 1.25em;
1504 | }
1505 | emu-intro h4,
1506 | emu-clause h4,
1507 | emu-annex h4 {
1508 |   font-size: 1.11em;
1509 | }
1510 | emu-intro h5,
1511 | emu-clause h5,
1512 | emu-annex h5 {
1513 |   font-size: 1em;
1514 | }
1515 | emu-intro h6,
1516 | emu-clause h6,
1517 | emu-annex h6 {
1518 |   font-size: 0.9em;
1519 | }
1520 | emu-intro emu-intro h1,
1521 | emu-clause emu-clause h1,
1522 | emu-annex emu-annex h1 {
1523 |   font-size: 1.56em;
1524 | }
1525 | emu-intro emu-intro h2,
1526 | emu-clause emu-clause h2,
1527 | emu-annex emu-annex h2 {
1528 |   font-size: 1.25em;
1529 | }
1530 | emu-intro emu-intro h3,
1531 | emu-clause emu-clause h3,
1532 | emu-annex emu-annex h3 {
1533 |   font-size: 1.11em;
1534 | }
1535 | emu-intro emu-intro h4,
1536 | emu-clause emu-clause h4,
1537 | emu-annex emu-annex h4 {
1538 |   font-size: 1em;
1539 | }
1540 | emu-intro emu-intro h5,
1541 | emu-clause emu-clause h5,
1542 | emu-annex emu-annex h5 {
1543 |   font-size: 0.9em;
1544 | }
1545 | emu-intro emu-intro emu-intro h1,
1546 | emu-clause emu-clause emu-clause h1,
1547 | emu-annex emu-annex emu-annex h1 {
1548 |   font-size: 1.25em;
1549 | }
1550 | emu-intro emu-intro emu-intro h2,
1551 | emu-clause emu-clause emu-clause h2,
1552 | emu-annex emu-annex emu-annex h2 {
1553 |   font-size: 1.11em;
1554 | }
1555 | emu-intro emu-intro emu-intro h3,
1556 | emu-clause emu-clause emu-clause h3,
1557 | emu-annex emu-annex emu-annex h3 {
1558 |   font-size: 1em;
1559 | }
1560 | emu-intro emu-intro emu-intro h4,
1561 | emu-clause emu-clause emu-clause h4,
1562 | emu-annex emu-annex emu-annex h4 {
1563 |   font-size: 0.9em;
1564 | }
1565 | emu-intro emu-intro emu-intro emu-intro h1,
1566 | emu-clause emu-clause emu-clause emu-clause h1,
1567 | emu-annex emu-annex emu-annex emu-annex h1 {
1568 |   font-size: 1.11em;
1569 | }
1570 | emu-intro emu-intro emu-intro emu-intro h2,
1571 | emu-clause emu-clause emu-clause emu-clause h2,
1572 | emu-annex emu-annex emu-annex emu-annex h2 {
1573 |   font-size: 1em;
1574 | }
1575 | emu-intro emu-intro emu-intro emu-intro h3,
1576 | emu-clause emu-clause emu-clause emu-clause h3,
1577 | emu-annex emu-annex emu-annex emu-annex h3 {
1578 |   font-size: 0.9em;
1579 | }
1580 | emu-intro emu-intro emu-intro emu-intro emu-intro h1,
1581 | emu-clause emu-clause emu-clause emu-clause emu-clause h1,
1582 | emu-annex emu-annex emu-annex emu-annex emu-annex h1 {
1583 |   font-size: 1em;
1584 | }
1585 | emu-intro emu-intro emu-intro emu-intro emu-intro h2,
1586 | emu-clause emu-clause emu-clause emu-clause emu-clause h2,
1587 | emu-annex emu-annex emu-annex emu-annex emu-annex h2 {
1588 |   font-size: 0.9em;
1589 | }
1590 | emu-intro emu-intro emu-intro emu-intro emu-intro emu-intro h1,
1591 | emu-clause emu-clause emu-clause emu-clause emu-clause emu-clause h1,
1592 | emu-annex emu-annex emu-annex emu-annex emu-annex emu-annex h1 {
1593 |   font-size: 0.9em;
1594 | }
1595 | 
1596 | emu-clause,
1597 | emu-intro,
1598 | emu-annex {
1599 |   display: block;
1600 | }
1601 | 
1602 | /* these values are twice the font-size for the <h1> titles for clauses */
1603 | emu-intro,
1604 | emu-clause,
1605 | emu-annex {
1606 |   margin-top: 4em;
1607 | }
1608 | emu-intro emu-intro,
1609 | emu-clause emu-clause,
1610 | emu-annex emu-annex {
1611 |   margin-top: 3.12em;
1612 | }
1613 | emu-intro emu-intro emu-intro,
1614 | emu-clause emu-clause emu-clause,
1615 | emu-annex emu-annex emu-annex {
1616 |   margin-top: 2.5em;
1617 | }
1618 | emu-intro emu-intro emu-intro emu-intro,
1619 | emu-clause emu-clause emu-clause emu-clause,
1620 | emu-annex emu-annex emu-annex emu-annex {
1621 |   margin-top: 2.22em;
1622 | }
1623 | emu-intro emu-intro emu-intro emu-intro emu-intro,
1624 | emu-clause emu-clause emu-clause emu-clause emu-clause,
1625 | emu-annex emu-annex emu-annex emu-annex emu-annex {
1626 |   margin-top: 2em;
1627 | }
1628 | emu-intro emu-intro emu-intro emu-intro emu-intro emu-intro,
1629 | emu-clause emu-clause emu-clause emu-clause emu-clause emu-clause,
1630 | emu-annex emu-annex emu-annex emu-annex emu-annex emu-annex {
1631 |   margin-top: 1.8em;
1632 | }
1633 | 
1634 | #spec-container > emu-intro:first-of-type,
1635 | #spec-container > emu-clause:first-of-type,
1636 | #spec-container > emu-annex:first-of-type {
1637 |   margin-top: 0;
1638 | }
1639 | 
1640 | /* Figures and tables */
1641 | figure {
1642 |   display: block;
1643 |   margin: 1em 0 3em 0;
1644 | }
1645 | figure object {
1646 |   display: block;
1647 |   margin: 0 auto;
1648 | }
1649 | figure table.real-table {
1650 |   margin: 0 auto;
1651 | }
1652 | figure figcaption {
1653 |   display: block;
1654 |   color: #555555;
1655 |   font-weight: bold;
1656 |   text-align: center;
1657 | }
1658 | 
1659 | emu-table table {
1660 |   margin: 0 auto;
1661 | }
1662 | 
1663 | emu-table table,
1664 | table.real-table {
1665 |   border-collapse: collapse;
1666 | }
1667 | 
1668 | emu-table td,
1669 | emu-table th,
1670 | table.real-table td,
1671 | table.real-table th {
1672 |   border: 1px solid black;
1673 |   padding: 0.4em;
1674 |   vertical-align: baseline;
1675 | }
1676 | emu-table th,
1677 | emu-table thead td,
1678 | table.real-table th {
1679 |   background-color: #eeeeee;
1680 | }
1681 | 
1682 | emu-table td {
1683 |   background: #fff;
1684 | }
1685 | 
1686 | /* Note: the left content edges of table.lightweight-table >tbody >tr >td
1687 |    and div.display line up. */
1688 | table.lightweight-table {
1689 |   border-collapse: collapse;
1690 |   margin: 0 0 0 1.5em;
1691 | }
1692 | table.lightweight-table td,
1693 | table.lightweight-table th {
1694 |   border: none;
1695 |   padding: 0 0.5em;
1696 |   vertical-align: baseline;
1697 | }
1698 | 
1699 | /* diff styles */
1700 | ins {
1701 |   background-color: #e0f8e0;
1702 |   text-decoration: none;
1703 |   border-bottom: 1px solid #396;
1704 | }
1705 | 
1706 | del {
1707 |   background-color: #fee;
1708 | }
1709 | 
1710 | ins.block,
1711 | del.block,
1712 | emu-production > ins,
1713 | emu-production > del,
1714 | emu-grammar > ins,
1715 | emu-grammar > del {
1716 |   display: block;
1717 | }
1718 | emu-rhs > ins,
1719 | emu-rhs > del {
1720 |   display: inline;
1721 | }
1722 | 
1723 | tr.ins > td > ins {
1724 |   border-bottom: none;
1725 | }
1726 | 
1727 | tr.ins > td {
1728 |   background-color: #e0f8e0;
1729 | }
1730 | 
1731 | tr.del > td {
1732 |   background-color: #fee;
1733 | }
1734 | 
1735 | /* Menu Styles */
1736 | #menu-toggle {
1737 |   font-size: 2em;
1738 | 
1739 |   position: fixed;
1740 |   top: 0;
1741 |   left: 0;
1742 |   width: 1.5em;
1743 |   height: 1.5em;
1744 |   z-index: 3;
1745 |   visibility: hidden;
1746 |   color: #1567a2;
1747 |   background-color: #fff;
1748 | 
1749 |   line-height: 1.5em;
1750 |   text-align: center;
1751 |   -webkit-touch-callout: none;
1752 |   -webkit-user-select: none;
1753 |   -khtml-user-select: none;
1754 |   -moz-user-select: none;
1755 |   -ms-user-select: none;
1756 |   user-select: none;
1757 | 
1758 |   cursor: pointer;
1759 | }
1760 | 
1761 | #menu {
1762 |   display: flex;
1763 |   flex-direction: column;
1764 |   width: 33%;
1765 |   height: 100vh;
1766 |   max-width: 500px;
1767 |   box-sizing: border-box;
1768 |   background-color: #ddd;
1769 |   overflow: hidden;
1770 |   transition: opacity 0.1s linear;
1771 |   padding: 0 5px;
1772 |   position: fixed;
1773 |   left: 0;
1774 |   top: 0;
1775 |   border-right: 2px solid #bbb;
1776 | 
1777 |   z-index: 2;
1778 | }
1779 | 
1780 | #menu-spacer {
1781 |   flex-basis: 33%;
1782 |   max-width: 500px;
1783 |   flex-grow: 0;
1784 |   flex-shrink: 0;
1785 | }
1786 | 
1787 | #menu a {
1788 |   color: #1567a2;
1789 | }
1790 | 
1791 | #menu.active {
1792 |   display: flex;
1793 |   opacity: 1;
1794 |   z-index: 2;
1795 | }
1796 | 
1797 | #menu-pins {
1798 |   flex-grow: 1;
1799 |   display: none;
1800 | }
1801 | 
1802 | #menu-pins.active {
1803 |   display: block;
1804 | }
1805 | 
1806 | #menu-pins-list {
1807 |   margin: 0;
1808 |   padding: 0;
1809 |   counter-reset: pins-counter;
1810 | }
1811 | 
1812 | #menu-pins-list > li:before {
1813 |   content: counter(pins-counter);
1814 |   counter-increment: pins-counter;
1815 |   display: inline-block;
1816 |   width: 25px;
1817 |   text-align: center;
1818 |   border: 1px solid #bbb;
1819 |   padding: 2px;
1820 |   margin: 4px;
1821 |   box-sizing: border-box;
1822 |   line-height: 1em;
1823 |   background-color: #ccc;
1824 |   border-radius: 4px;
1825 | }
1826 | #menu-toc > ol {
1827 |   padding: 0;
1828 |   flex-grow: 1;
1829 | }
1830 | 
1831 | #menu-toc > ol li {
1832 |   padding: 0;
1833 | }
1834 | 
1835 | #menu-toc > ol,
1836 | #menu-toc > ol ol {
1837 |   list-style-type: none;
1838 |   margin: 0;
1839 |   padding: 0;
1840 | }
1841 | 
1842 | #menu-toc > ol ol {
1843 |   padding-left: 0.75em;
1844 | }
1845 | 
1846 | #menu-toc li {
1847 |   text-overflow: ellipsis;
1848 |   overflow: hidden;
1849 |   white-space: nowrap;
1850 | }
1851 | 
1852 | #menu-toc .item-toggle {
1853 |   display: inline-block;
1854 |   transform: rotate(-45deg) translate(-5px, -5px);
1855 |   transition: transform 0.1s ease;
1856 |   text-align: center;
1857 |   width: 20px;
1858 | 
1859 |   color: #aab;
1860 | 
1861 |   -webkit-touch-callout: none;
1862 |   -webkit-user-select: none;
1863 |   -khtml-user-select: none;
1864 |   -moz-user-select: none;
1865 |   -ms-user-select: none;
1866 |   user-select: none;
1867 | 
1868 |   cursor: pointer;
1869 | }
1870 | 
1871 | #menu-toc .item-toggle-none {
1872 |   display: inline-block;
1873 |   width: 20px;
1874 | }
1875 | 
1876 | #menu-toc li.active > .item-toggle {
1877 |   transform: rotate(45deg) translate(-5px, -5px);
1878 | }
1879 | 
1880 | #menu-toc li > ol {
1881 |   display: none;
1882 | }
1883 | 
1884 | #menu-toc li.active > ol {
1885 |   display: block;
1886 | }
1887 | 
1888 | #menu-toc li.revealed > a {
1889 |   background-color: #bbb;
1890 |   font-weight: bold;
1891 |   /*
1892 |   background-color: #222;
1893 |   color: #c6d8e4;
1894 |   */
1895 | }
1896 | 
1897 | #menu-toc li.revealed-leaf > a {
1898 |   color: #206ca7;
1899 |   /*
1900 |   background-color: #222;
1901 |   color: #c6d8e4;
1902 |   */
1903 | }
1904 | 
1905 | #menu-toc li.revealed > .item-toggle {
1906 |   transform: rotate(45deg) translate(-5px, -5px);
1907 | }
1908 | 
1909 | #menu-toc li.revealed > ol {
1910 |   display: block;
1911 | }
1912 | 
1913 | #menu-toc li > a {
1914 |   padding: 2px 5px;
1915 | }
1916 | 
1917 | #menu > * {
1918 |   margin-bottom: 5px;
1919 | }
1920 | 
1921 | .menu-pane-header {
1922 |   padding: 0 5px;
1923 |   text-transform: uppercase;
1924 |   background-color: #aaa;
1925 |   color: #335;
1926 |   font-weight: bold;
1927 |   letter-spacing: 2px;
1928 |   flex-grow: 0;
1929 |   flex-shrink: 0;
1930 |   font-size: 0.8em;
1931 | }
1932 | 
1933 | .menu-pane-header emu-opt,
1934 | .menu-pane-header emu-t,
1935 | .menu-pane-header emu-nt {
1936 |   margin-right: 0px;
1937 |   display: inline;
1938 |   color: inherit;
1939 | }
1940 | 
1941 | .menu-pane-header emu-rhs {
1942 |   display: inline;
1943 |   padding-left: 0px;
1944 |   text-indent: 0px;
1945 | }
1946 | 
1947 | .menu-pane-header emu-geq {
1948 |   margin-left: 0px;
1949 | }
1950 | 
1951 | a.menu-pane-header-production {
1952 |   color: inherit;
1953 | }
1954 | 
1955 | .menu-pane-header-production {
1956 |   text-transform: none;
1957 |   letter-spacing: 1.5px;
1958 |   padding-left: 0.5em;
1959 | }
1960 | 
1961 | #menu-toc {
1962 |   display: flex;
1963 |   flex-direction: column;
1964 |   width: 100%;
1965 |   overflow: hidden;
1966 |   flex-grow: 1;
1967 | }
1968 | 
1969 | #menu-toc ol.toc {
1970 |   overflow-x: hidden;
1971 |   overflow-y: auto;
1972 | }
1973 | 
1974 | #menu-search {
1975 |   position: relative;
1976 |   flex-grow: 0;
1977 |   flex-shrink: 0;
1978 |   width: 100%;
1979 | 
1980 |   display: flex;
1981 |   flex-direction: column;
1982 | 
1983 |   max-height: 300px;
1984 | }
1985 | 
1986 | #menu-trace-list {
1987 |   display: none;
1988 | }
1989 | 
1990 | #menu-search-box {
1991 |   box-sizing: border-box;
1992 |   display: block;
1993 |   width: 100%;
1994 |   margin: 5px 0 0 0;
1995 |   font-size: 1em;
1996 |   padding: 2px;
1997 |   background-color: #bbb;
1998 |   border: 1px solid #999;
1999 | }
2000 | 
2001 | #menu-search-results {
2002 |   overflow-x: hidden;
2003 |   overflow-y: auto;
2004 | }
2005 | 
2006 | li.menu-search-result-clause:before {
2007 |   content: 'clause';
2008 |   width: 40px;
2009 |   display: inline-block;
2010 |   text-align: right;
2011 |   padding-right: 1ex;
2012 |   color: #666;
2013 |   font-size: 75%;
2014 | }
2015 | li.menu-search-result-op:before {
2016 |   content: 'op';
2017 |   width: 40px;
2018 |   display: inline-block;
2019 |   text-align: right;
2020 |   padding-right: 1ex;
2021 |   color: #666;
2022 |   font-size: 75%;
2023 | }
2024 | 
2025 | li.menu-search-result-prod:before {
2026 |   content: 'prod';
2027 |   width: 40px;
2028 |   display: inline-block;
2029 |   text-align: right;
2030 |   padding-right: 1ex;
2031 |   color: #666;
2032 |   font-size: 75%;
2033 | }
2034 | 
2035 | li.menu-search-result-term:before {
2036 |   content: 'term';
2037 |   width: 40px;
2038 |   display: inline-block;
2039 |   text-align: right;
2040 |   padding-right: 1ex;
2041 |   color: #666;
2042 |   font-size: 75%;
2043 | }
2044 | 
2045 | #menu-search-results ul {
2046 |   padding: 0 5px;
2047 |   margin: 0;
2048 | }
2049 | 
2050 | #menu-search-results li {
2051 |   white-space: nowrap;
2052 |   text-overflow: ellipsis;
2053 | }
2054 | 
2055 | #menu-trace-list {
2056 |   counter-reset: item;
2057 |   margin: 0 0 0 20px;
2058 |   padding: 0;
2059 | }
2060 | #menu-trace-list li {
2061 |   display: block;
2062 |   white-space: nowrap;
2063 | }
2064 | 
2065 | #menu-trace-list li .secnum:after {
2066 |   content: ' ';
2067 | }
2068 | #menu-trace-list li:before {
2069 |   content: counter(item) ' ';
2070 |   background-color: #222;
2071 |   counter-increment: item;
2072 |   color: #999;
2073 |   width: 20px;
2074 |   height: 20px;
2075 |   line-height: 20px;
2076 |   display: inline-block;
2077 |   text-align: center;
2078 |   margin: 2px 4px 2px 0;
2079 | }
2080 | 
2081 | @media (max-width: 1000px) {
2082 |   body {
2083 |     margin: 0;
2084 |     display: block;
2085 |   }
2086 | 
2087 |   #menu {
2088 |     display: none;
2089 |     padding-top: 3em;
2090 |     width: 450px;
2091 |   }
2092 | 
2093 |   #menu.active {
2094 |     position: fixed;
2095 |     height: 100%;
2096 |     left: 0;
2097 |     top: 0;
2098 |     right: 300px;
2099 |   }
2100 | 
2101 |   #menu-toggle {
2102 |     visibility: visible;
2103 |   }
2104 | 
2105 |   #spec-container {
2106 |     padding: 0 5px;
2107 |   }
2108 | 
2109 |   #references-pane-spacer {
2110 |     display: none;
2111 |   }
2112 | }
2113 | 
2114 | @media only screen and (max-width: 800px) {
2115 |   #menu {
2116 |     width: 100%;
2117 |   }
2118 | 
2119 |   h1 .secnum:empty {
2120 |     margin: 0;
2121 |     padding: 0;
2122 |   }
2123 | }
2124 | 
2125 | /* Toolbox */
2126 | .toolbox-container {
2127 |   position: absolute;
2128 |   display: none;
2129 |   padding-bottom: 7px;
2130 | }
2131 | 
2132 | .toolbox-container.active {
2133 |   display: inline-block;
2134 | }
2135 | 
2136 | .toolbox {
2137 |   position: relative;
2138 |   background: #ddd;
2139 |   border: 1px solid #aaa;
2140 |   color: #eee;
2141 |   padding: 5px;
2142 |   border-radius: 3px;
2143 | }
2144 | 
2145 | .toolbox a {
2146 |   text-decoration: none;
2147 |   padding: 0 5px;
2148 | }
2149 | 
2150 | .toolbox a:hover {
2151 |   text-decoration: underline;
2152 | }
2153 | 
2154 | .toolbox:after,
2155 | .toolbox:before {
2156 |   top: 100%;
2157 |   left: 15px;
2158 |   border: solid transparent;
2159 |   content: ' ';
2160 |   height: 0;
2161 |   width: 0;
2162 |   position: absolute;
2163 |   pointer-events: none;
2164 | }
2165 | 
2166 | .toolbox:after {
2167 |   border-color: rgba(0, 0, 0, 0);
2168 |   border-top-color: #ddd;
2169 |   border-width: 10px;
2170 |   margin-left: -10px;
2171 | }
2172 | .toolbox:before {
2173 |   border-color: rgba(204, 204, 204, 0);
2174 |   border-top-color: #aaa;
2175 |   border-width: 12px;
2176 |   margin-left: -12px;
2177 | }
2178 | 
2179 | #references-pane-container {
2180 |   position: fixed;
2181 |   bottom: 0;
2182 |   left: 0;
2183 |   right: 0;
2184 |   height: 250px;
2185 |   display: none;
2186 |   background-color: #ddd;
2187 |   z-index: 1;
2188 | }
2189 | 
2190 | #references-pane-table-container {
2191 |   overflow-x: hidden;
2192 |   overflow-y: auto;
2193 | }
2194 | 
2195 | #references-pane-spacer {
2196 |   flex-basis: 33%;
2197 |   max-width: 500px;
2198 | }
2199 | 
2200 | #references-pane {
2201 |   flex-grow: 1;
2202 |   overflow: hidden;
2203 |   display: flex;
2204 |   flex-direction: column;
2205 | }
2206 | 
2207 | #references-pane-container.active {
2208 |   display: flex;
2209 | }
2210 | 
2211 | #references-pane-close:after {
2212 |   content: '✖';
2213 |   float: right;
2214 |   cursor: pointer;
2215 | }
2216 | 
2217 | #references-pane table tr td:first-child {
2218 |   text-align: right;
2219 |   padding-right: 5px;
2220 | }
2221 | 
2222 | @media print {
2223 |   #menu-toggle {
2224 |     display: none;
2225 |   }
2226 | }
2227 | 
2228 | [normative-optional] {
2229 |   border-left: 5px solid #ff6600;
2230 |   padding: 0.5em;
2231 |   display: block;
2232 |   background: #ffeedd;
2233 | }
2234 | 
2235 | .normative-optional-tag {
2236 |   text-transform: uppercase;
2237 |   color: #884400;
2238 | }
2239 | 
2240 | .normative-optional-tag a {
2241 |   color: #884400;
2242 | }
2243 | </style></head><body><div id="menu-toggle">☰</div><div id="menu-spacer"></div><div id="menu"><div id="menu-search"><input type="text" id="menu-search-box" placeholder="Search..."><div id="menu-search-results" class="inactive"></div></div><div id="menu-pins"><div class="menu-pane-header">Pins</div><ul id="menu-pins-list"></ul></div><div class="menu-pane-header">Table of Contents</div><div id="menu-toc"><ol class="toc"><li><span class="item-toggle-none"></span><a href="#sec-scope" title="Scope"><span class="secnum">1</span> Scope</a></li><li><span class="item-toggle">◢</span><a href="#sec-properties-of-the-array-prototype-object" title="Properties of the Array Prototype Object (22.1.3)"><span class="secnum">2</span> Properties of the Array Prototype Object (</a><a href="https://tc39.es/ecma262/#sec-properties-of-the-array-prototype-object">22.1.3</a>)<ol class="toc"><li><span class="item-toggle-none"></span><a href="#sec-array.prototype.groupby" title="Array.prototype.groupBy ( callbackfn [ , thisArg ] )"><span class="secnum">2.1</span> Array.prototype.groupBy ( <var>callbackfn</var> [ , <var>thisArg</var> ] )</a></li><li><span class="item-toggle-none"></span><a href="#sec-array.prototype.groupbymap" title="Array.prototype.groupByMap ( callbackfn [ , thisArg ] )"><span class="secnum">2.2</span> Array.prototype.groupByMap ( <var>callbackfn</var> [ , <var>thisArg</var> ] )</a></li><li><span class="item-toggle-none"></span><a href="#sec-add-value-to-keyed-group" title="
2244 |       AddValueToKeyedGroup (
2245 |         groups: a List of Records that have [[Key]] and [[Elements]] fields,
2246 |         key: an ECMAScript language value,
2247 |         value: an ECMAScript language value,
2248 |       )
2249 |     "><span class="secnum">2.3</span> 
2250 |       AddValueToKeyedGroup (
2251 |         <var>groups</var>: a List of Records that have [[Key]] and [[Elements]] fields,
2252 |         <var>key</var>: an ECMAScript language value,
2253 |         <var>value</var>: an ECMAScript language value,
2254 |       )
2255 |     </a></li></ol></li><li><span class="item-toggle-none"></span><a href="#sec-copyright-and-software-license" title="Copyright &amp; Software License"><span class="secnum">A</span> Copyright &amp; Software License</a></li></ol></div></div><div id="spec-container"><h1 class="version">Stage 2 Draft / October 30, 2021</h1><h1 class="title">Array Grouping</h1>
2256 | 
2257 | <emu-clause id="sec-scope">
2258 |   <h1><span class="secnum">1</span> Scope</h1>
2259 |   <p>
2260 |     This is the spec text of the <a href="https://github.com/tc39/proposal-array-grouping/">Array Grouping proposal</a> in ECMAScript.
2261 |   </p>
2262 | </emu-clause>
2263 | 
2264 | <emu-clause id="sec-properties-of-the-array-prototype-object">
2265 |   <h1><span class="secnum">2</span> Properties of the Array Prototype Object (<a href="https://tc39.es/ecma262/#sec-properties-of-the-array-prototype-object">22.1.3</a>)</h1>
2266 | 
2267 |   <ins class="block">
2268 |   <emu-clause id="sec-array.prototype.groupby">
2269 |     <h1><span class="secnum">2.1</span> Array.prototype.groupBy ( <var>callbackfn</var> [ , <var>thisArg</var> ] )</h1>
2270 |     <emu-note><span class="note">Note 1</span><div class="note-contents">
2271 |       <p><var>callbackfn</var> should be a function that accepts three arguments and returns a value that is coercible to a property. <code>groupBy</code> calls <var>callbackfn</var> once for each element in the array, in ascending order, and constructs a new object of arrays, where the property key is the return value and array is filled with the items that return that property key.</p>
2272 |       <p>If a <var>thisArg</var> parameter is provided, it will be used as the <emu-val>this</emu-val> value for each invocation of <var>callbackfn</var>. If it is not provided, <emu-val>undefined</emu-val> is used instead.</p>
2273 |       <p><var>callbackfn</var> is called with three arguments: the value of the element, the index of the element, and the object being traversed.</p>
2274 |       <p><code>groupBy</code> does not directly mutate the object on which it is called but the object may be mutated by the calls to <var>callbackfn</var>.</p>
2275 |       <p>The range of elements processed by <code>groupBy</code> is set before the first call to <var>callbackfn</var>. Elements which are appended to the array after the call to <code>groupBy</code> begins will not be visited by <var>callbackfn</var>. If existing elements of the array are changed their value as passed to <var>callbackfn</var> will be the value at the time <code>groupBy</code> visits them; elements that are deleted after the call to <code>groupBy</code> begins and before being visited are still visited and are either looked up from the prototype or are <emu-val>undefined</emu-val>.</p>
2276 |       <p>The return value of <code>groupBy</code> is an object that does not inherit from <var>Object.prototype</var>.</p>
2277 |     </div></emu-note>
2278 |     <p>When the <code>groupBy</code> method is called with one or two arguments, the following steps are taken:</p>
2279 |     <emu-alg><ol><li>Let <var>O</var> be ?&nbsp;<emu-xref aoid="ToObject" id="_ref_0"><a href="https://tc39.es/ecma262/#sec-toobject">ToObject</a></emu-xref>(<emu-val>this</emu-val> value).</li><li>Let <var>len</var> be ?&nbsp;<emu-xref aoid="LengthOfArrayLike" id="_ref_1"><a href="https://tc39.es/ecma262/#sec-lengthofarraylike">LengthOfArrayLike</a></emu-xref>(<var>O</var>).</li><li>If <emu-xref aoid="IsCallable" id="_ref_2"><a href="https://tc39.es/ecma262/#sec-iscallable">IsCallable</a></emu-xref>(<var>callbackfn</var>) is <emu-val>false</emu-val>, throw a <emu-val>TypeError</emu-val> exception.</li><li>Let <var>k</var> be 0.</li><li>Let <var>groups</var> be a new empty <emu-xref href="#sec-list-and-record-specification-type"><a href="https://tc39.es/ecma262/#sec-list-and-record-specification-type">List</a></emu-xref>.</li><li>Repeat, while <var>k</var> &lt; <var>len</var><ol><li>Let <var>Pk</var> be !&nbsp;<emu-xref aoid="ToString" id="_ref_3"><a href="https://tc39.es/ecma262/#sec-tostring">ToString</a></emu-xref>(<emu-xref href="#𝔽"><a href="https://tc39.es/ecma262/#𝔽">𝔽</a></emu-xref>(<var>k</var>)).</li><li>Let <var>kValue</var> be ?&nbsp;<emu-xref aoid="Get" id="_ref_4"><a href="https://tc39.es/ecma262/#sec-get-o-p">Get</a></emu-xref>(<var>O</var>, <var>Pk</var>).</li><li>Let <var>propertyKey</var> be ?&nbsp;<emu-xref aoid="ToPropertyKey" id="_ref_5"><a href="https://tc39.es/ecma262/#sec-topropertykey">ToPropertyKey</a></emu-xref>(? <emu-xref aoid="Call" id="_ref_6"><a href="https://tc39.es/ecma262/#sec-call">Call</a></emu-xref>(<var>callbackfn</var>, <var>thisArg</var>, « <var>kValue</var>, <emu-xref href="#𝔽"><a href="https://tc39.es/ecma262/#𝔽">𝔽</a></emu-xref>(<var>k</var>), <var>O</var> »)).</li><li>Perform !&nbsp;AddValueToKeyedGroup(<var>groups</var>, <var>propertyKey</var>, <var>kValue</var>).</li><li>Set <var>k</var> to <var>k</var> + 1.</li></ol></li><li>Let <var>obj</var> be !&nbsp;OrdinaryObjectCreate(<emu-val>null</emu-val>).</li><li>For each <emu-xref href="#sec-list-and-record-specification-type"><a href="https://tc39.es/ecma262/#sec-list-and-record-specification-type">Record</a></emu-xref> { [[Key]], [[Elements]] } <var>g</var> of <var>groups</var>, do<ol><li>Let <var>elements</var> be !&nbsp;<emu-xref aoid="CreateArrayFromList" id="_ref_7"><a href="https://tc39.es/ecma262/#sec-createarrayfromlist">CreateArrayFromList</a></emu-xref>(<var>g</var>.[[Elements]]).</li><li>Perform !&nbsp;<emu-xref aoid="CreateDataPropertyOrThrow" id="_ref_8"><a href="https://tc39.es/ecma262/#sec-createdatapropertyorthrow">CreateDataPropertyOrThrow</a></emu-xref>(<var>obj</var>, <var>g</var>.[[Key]], <var>elements</var>).</li></ol></li><li>Return <var>obj</var>.</li></ol></emu-alg>
2280 |     <emu-note><span class="note">Note 2</span><div class="note-contents">
2281 |       <p>The <code>groupBy</code> function is intentionally generic; it does not require that its <emu-val>this</emu-val> value be an Array object. Therefore it can be transferred to other kinds of objects for use as a method.</p>
2282 |     </div></emu-note>
2283 |   </emu-clause>
2284 |   </ins>
2285 | 
2286 |   <ins class="block">
2287 |   <emu-clause id="sec-array.prototype.groupbymap">
2288 |     <h1><span class="secnum">2.2</span> Array.prototype.groupByMap ( <var>callbackfn</var> [ , <var>thisArg</var> ] )</h1>
2289 |     <emu-note><span class="note">Note 1</span><div class="note-contents">
2290 |       <p><var>callbackfn</var> should be a function that accepts three arguments and returns any value. <code>groupByMap</code> calls <var>callbackfn</var> once for each element in the array, in ascending order, and constructs a new Map of arrays, where the key is the return value and array is filled with the items that return that key.</p>
2291 |       <p>If a <var>thisArg</var> parameter is provided, it will be used as the <emu-val>this</emu-val> value for each invocation of <var>callbackfn</var>. If it is not provided, <emu-val>undefined</emu-val> is used instead.</p>
2292 |       <p><var>callbackfn</var> is called with three arguments: the value of the element, the index of the element, and the object being traversed.</p>
2293 |       <p><code>groupByMap</code> does not directly mutate the object on which it is called but the object may be mutated by the calls to <var>callbackfn</var>.</p>
2294 |       <p>The range of elements processed by <code>groupByMap</code> is set before the first call to <var>callbackfn</var>. Elements which are appended to the array after the call to <code>groupByMap</code> begins will not be visited by <var>callbackfn</var>. If existing elements of the array are changed their value as passed to <var>callbackfn</var> will be the value at the time <code>groupByMap</code> visits them; elements that are deleted after the call to <code>groupByMap</code> begins and before being visited are still visited and are either looked up from the prototype or are <emu-val>undefined</emu-val>.</p>
2295 |       <p>The return value of <code>groupByMap</code> is a Map.</p>
2296 |     </div></emu-note>
2297 |     <p>When the <code>groupByMap</code> method is called with one or two arguments, the following steps are taken:</p>
2298 |     <emu-alg><ol><li>Let <var>O</var> be ?&nbsp;<emu-xref aoid="ToObject" id="_ref_9"><a href="https://tc39.es/ecma262/#sec-toobject">ToObject</a></emu-xref>(<emu-val>this</emu-val> value).</li><li>Let <var>len</var> be ?&nbsp;<emu-xref aoid="LengthOfArrayLike" id="_ref_10"><a href="https://tc39.es/ecma262/#sec-lengthofarraylike">LengthOfArrayLike</a></emu-xref>(<var>O</var>).</li><li>If <emu-xref aoid="IsCallable" id="_ref_11"><a href="https://tc39.es/ecma262/#sec-iscallable">IsCallable</a></emu-xref>(<var>callbackfn</var>) is <emu-val>false</emu-val>, throw a <emu-val>TypeError</emu-val> exception.</li><li>Let <var>k</var> be 0.</li><li>Let <var>groups</var> be a new empty <emu-xref href="#sec-list-and-record-specification-type"><a href="https://tc39.es/ecma262/#sec-list-and-record-specification-type">List</a></emu-xref>.</li><li>Repeat, while <var>k</var> &lt; <var>len</var><ol><li>Let <var>Pk</var> be !&nbsp;<emu-xref aoid="ToString" id="_ref_12"><a href="https://tc39.es/ecma262/#sec-tostring">ToString</a></emu-xref>(<emu-xref href="#𝔽"><a href="https://tc39.es/ecma262/#𝔽">𝔽</a></emu-xref>(<var>k</var>)).</li><li>Let <var>kValue</var> be ?&nbsp;<emu-xref aoid="Get" id="_ref_13"><a href="https://tc39.es/ecma262/#sec-get-o-p">Get</a></emu-xref>(<var>O</var>, <var>Pk</var>).</li><li>Let <var>key</var> be ?&nbsp;<emu-xref aoid="Call" id="_ref_14"><a href="https://tc39.es/ecma262/#sec-call">Call</a></emu-xref>(<var>callbackfn</var>, <var>thisArg</var>, « <var>kValue</var>, <emu-xref href="#𝔽"><a href="https://tc39.es/ecma262/#𝔽">𝔽</a></emu-xref>(<var>k</var>), <var>O</var> »).</li><li>If <var>key</var> is <emu-val>-0</emu-val><sub>𝔽</sub>, set <var>key</var> to <emu-val>+0</emu-val><sub>𝔽</sub>.</li><li>Perform !&nbsp;AddValueToKeyedGroup(<var>groups</var>, <var>key</var>, <var>kValue</var>).</li><li>Set <var>k</var> to <var>k</var> + 1.</li></ol></li><li>Let <var>map</var> be !&nbsp;<emu-xref aoid="Construct" id="_ref_15"><a href="https://tc39.es/ecma262/#sec-construct">Construct</a></emu-xref>(<emu-xref href="#sec-map-constructor"><a href="https://tc39.es/ecma262/#sec-map-constructor">%Map%</a></emu-xref>).</li><li>For each <emu-xref href="#sec-list-and-record-specification-type"><a href="https://tc39.es/ecma262/#sec-list-and-record-specification-type">Record</a></emu-xref> { [[Key]], [[Elements]] } <var>g</var> of <var>groups</var>, do<ol><li>Let <var>elements</var> be !&nbsp;<emu-xref aoid="CreateArrayFromList" id="_ref_16"><a href="https://tc39.es/ecma262/#sec-createarrayfromlist">CreateArrayFromList</a></emu-xref>(<var>g</var>.[[Elements]]).</li><li>Let <var>entry</var> be the <emu-xref href="#sec-list-and-record-specification-type"><a href="https://tc39.es/ecma262/#sec-list-and-record-specification-type">Record</a></emu-xref> { [[Key]]: <var>g</var>.[[Key]], [[Value]]: <var>elements</var> }.</li><li>Append <var>entry</var> as the last element of <var>map</var>.[[MapData]].</li></ol></li><li>Return <var>map</var>.</li></ol></emu-alg>
2299 |     <emu-note><span class="note">Note 2</span><div class="note-contents">
2300 |       <p>The <code>groupBy</code> function is intentionally generic; it does not require that its <emu-val>this</emu-val> value be an Array object. Therefore it can be transferred to other kinds of objects for use as a method.</p>
2301 |     </div></emu-note>
2302 |   </emu-clause>
2303 | 
2304 |   <emu-clause id="sec-add-value-to-keyed-group" type="abstract operation">
2305 |     <h1><span class="secnum">2.3</span> 
2306 |       AddValueToKeyedGroup (
2307 |         <var>groups</var>: a List of Records that have [[Key]] and [[Elements]] fields,
2308 |         <var>key</var>: an ECMAScript language value,
2309 |         <var>value</var>: an ECMAScript language value,
2310 |       )
2311 |     </h1>
2312 |     <emu-alg><ol><li>If <var>groups</var> contains a <emu-xref href="#sec-list-and-record-specification-type"><a href="https://tc39.es/ecma262/#sec-list-and-record-specification-type">Record</a></emu-xref> <var>g</var> such that !&nbsp;<emu-xref aoid="SameValueZero" id="_ref_17"><a href="https://tc39.es/ecma262/#sec-samevaluezero">SameValueZero</a></emu-xref>(<var>g</var>.[[Key]], <var>key</var>) is <emu-val>true</emu-val>, then<ol><li><emu-xref href="#assert"><a href="https://tc39.es/ecma262/#assert">Assert</a></emu-xref>: exactly one element of <var>groups</var> meets this criteria.</li><li>Append <var>value</var> as the last element of <var>g</var>.[[Elements]].</li></ol></li><li>Else,<ol><li>Let <var>group</var> be the <emu-xref href="#sec-list-and-record-specification-type"><a href="https://tc39.es/ecma262/#sec-list-and-record-specification-type">Record</a></emu-xref> { [[Key]]: <var>key</var>, [[Elements]]: « <var>value</var> » }.</li><li>Append <var>group</var> as the last element of <var>groups</var>.</li></ol></li></ol></emu-alg>
2313 |   </emu-clause>
2314 |   </ins>
2315 | </emu-clause><emu-annex id="sec-copyright-and-software-license">
2316 |       <h1><span class="secnum">A</span> Copyright &amp; Software License</h1>
2317 |       
2318 |       <h2>Copyright Notice</h2>
2319 |       <p>© 2021 Justin Ridgewell</p>
2320 | 
2321 |       <h2>Software License</h2>
2322 |       <p>All Software contained in this document ("Software") is protected by copyright and is being made available under the "BSD License", included below. This Software may be subject to third party rights (rights from parties other than Ecma International), including patent rights, and no licenses under such third party rights are granted under this license even if the third party concerned is a member of Ecma International. SEE THE ECMA CODE OF CONDUCT IN PATENT MATTERS AVAILABLE AT https://ecma-international.org/memento/codeofconduct.htm FOR INFORMATION REGARDING THE LICENSING OF PATENT CLAIMS THAT ARE REQUIRED TO IMPLEMENT ECMA INTERNATIONAL STANDARDS.</p>
2323 | 
2324 | <p>Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:</p>
2325 | 
2326 | <ol>
2327 |   <li>Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.</li>
2328 |   <li>Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.</li>
2329 |   <li>Neither the name of the authors nor Ecma International may be used to endorse or promote products derived from this software without specific prior written permission.</li>
2330 | </ol>
2331 | 
2332 | <p>THIS SOFTWARE IS PROVIDED BY THE ECMA INTERNATIONAL "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL ECMA INTERNATIONAL BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.</p>
2333 | 
2334 |     </emu-annex>
2335 | </div></body>


--------------------------------------------------------------------------------
/package.json:
--------------------------------------------------------------------------------
 1 | {
 2 |   "private": true,
 3 |   "name": "proposal-array-grouping",
 4 |   "description": "A proposal to make grouping of array items easier",
 5 |   "scripts": {
 6 |     "start": "npm run build-loose -- --watch",
 7 |     "build": "npm run build-loose -- --strict",
 8 |     "build-loose": "ecmarkup --verbose spec.emu index.html"
 9 |   },
10 |   "homepage": "https://github.com/tc39/proposal-array-grouping#readme",
11 |   "repository": {
12 |     "type": "git",
13 |     "url": "git+https://github.com/tc39/proposal-array-grouping.git"
14 |   },
15 |   "license": "MIT",
16 |   "devDependencies": {
17 |     "ecmarkup": "^7.0.3"
18 |   }
19 | }
20 | 


--------------------------------------------------------------------------------
/spec.emu:
--------------------------------------------------------------------------------
  1 | <!doctype html>
  2 | <meta charset="utf8">
  3 | <link rel="stylesheet" href="./spec.css">
  4 | <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/highlight.js/8.4/styles/github.min.css">
  5 | <script src="./spec.js"></script>
  6 | <pre class="metadata">
  7 | title: Array Grouping
  8 | status: proposal
  9 | stage: 2
 10 | contributors: Justin Ridgewell
 11 | location: https://tc39.es/proposal-array-grouping/
 12 | </pre>
 13 | 
 14 | <emu-clause id="sec-scope">
 15 |   <h1>Scope</h1>
 16 |   <p>
 17 |     This is the spec text of the <a href="https://github.com/tc39/proposal-array-grouping/">Array Grouping proposal</a> in ECMAScript.
 18 |   </p>
 19 | </emu-clause>
 20 | 
 21 | <emu-clause id="sec-properties-of-the-array-prototype-object">
 22 |   <h1>Properties of the Array Prototype Object (<a href="https://tc39.es/ecma262/#sec-properties-of-the-array-prototype-object">22.1.3</a>)</h1>
 23 | 
 24 |   <ins class="block">
 25 |   <emu-clause id="sec-array.prototype.groupby">
 26 |     <h1>Array.prototype.groupBy ( _callbackfn_ [ , _thisArg_ ] )</h1>
 27 |     <emu-note>
 28 |       <p>_callbackfn_ should be a function that accepts three arguments and returns a value that is coercible to a property. `groupBy` calls _callbackfn_ once for each element in the array, in ascending order, and constructs a new object of arrays, where the property key is the return value and array is filled with the items that return that property key.</p>
 29 |       <p>If a _thisArg_ parameter is provided, it will be used as the *this* value for each invocation of _callbackfn_. If it is not provided, *undefined* is used instead.</p>
 30 |       <p>_callbackfn_ is called with three arguments: the value of the element, the index of the element, and the object being traversed.</p>
 31 |       <p>`groupBy` does not directly mutate the object on which it is called but the object may be mutated by the calls to _callbackfn_.</p>
 32 |       <p>The range of elements processed by `groupBy` is set before the first call to _callbackfn_. Elements which are appended to the array after the call to `groupBy` begins will not be visited by _callbackfn_. If existing elements of the array are changed their value as passed to _callbackfn_ will be the value at the time `groupBy` visits them; elements that are deleted after the call to `groupBy` begins and before being visited are still visited and are either looked up from the prototype or are *undefined*.</p>
 33 |       <p>The return value of `groupBy` is an object that does not inherit from _Object.prototype_.</p>
 34 |     </emu-note>
 35 |     <p>When the `groupBy` method is called with one or two arguments, the following steps are taken:</p>
 36 |     <emu-alg>
 37 |       1. Let _O_ be ? ToObject(*this* value).
 38 |       1. Let _len_ be ? LengthOfArrayLike(_O_).
 39 |       1. If IsCallable(_callbackfn_) is *false*, throw a *TypeError* exception.
 40 |       1. Let _k_ be 0.
 41 |       1. Let _groups_ be a new empty List.
 42 |       1. Repeat, while _k_ &lt; _len_
 43 |         1. Let _Pk_ be ! ToString(𝔽(_k_)).
 44 |         1. Let _kValue_ be ? Get(_O_, _Pk_).
 45 |         1. Let _propertyKey_ be ? ToPropertyKey(? Call(_callbackfn_, _thisArg_, &laquo; _kValue_, 𝔽(_k_), _O_ &raquo;)).
 46 |         1. Perform ! AddValueToKeyedGroup(_groups_, _propertyKey_, _kValue_).
 47 |         1. Set _k_ to _k_ + 1.
 48 |       1. Let _obj_ be ! OrdinaryObjectCreate(*null*).
 49 |       1. For each Record { [[Key]], [[Elements]] } _g_ of _groups_, do
 50 |         1. Let _elements_ be ! CreateArrayFromList(_g_.[[Elements]]).
 51 |         1. Perform ! CreateDataPropertyOrThrow(_obj_, _g_.[[Key]], _elements_).
 52 |       1. Return _obj_.
 53 |     </emu-alg>
 54 |     <emu-note>
 55 |       <p>The `groupBy` function is intentionally generic; it does not require that its *this* value be an Array object. Therefore it can be transferred to other kinds of objects for use as a method.</p>
 56 |     </emu-note>
 57 |   </emu-clause>
 58 |   </ins>
 59 | 
 60 |   <ins class="block">
 61 |   <emu-clause id="sec-array.prototype.groupbymap">
 62 |     <h1>Array.prototype.groupByMap ( _callbackfn_ [ , _thisArg_ ] )</h1>
 63 |     <emu-note>
 64 |       <p>_callbackfn_ should be a function that accepts three arguments and returns any value. `groupByMap` calls _callbackfn_ once for each element in the array, in ascending order, and constructs a new Map of arrays, where the key is the return value and array is filled with the items that return that key.</p>
 65 |       <p>If a _thisArg_ parameter is provided, it will be used as the *this* value for each invocation of _callbackfn_. If it is not provided, *undefined* is used instead.</p>
 66 |       <p>_callbackfn_ is called with three arguments: the value of the element, the index of the element, and the object being traversed.</p>
 67 |       <p>`groupByMap` does not directly mutate the object on which it is called but the object may be mutated by the calls to _callbackfn_.</p>
 68 |       <p>The range of elements processed by `groupByMap` is set before the first call to _callbackfn_. Elements which are appended to the array after the call to `groupByMap` begins will not be visited by _callbackfn_. If existing elements of the array are changed their value as passed to _callbackfn_ will be the value at the time `groupByMap` visits them; elements that are deleted after the call to `groupByMap` begins and before being visited are still visited and are either looked up from the prototype or are *undefined*.</p>
 69 |       <p>The return value of `groupByMap` is a Map.</p>
 70 |     </emu-note>
 71 |     <p>When the `groupByMap` method is called with one or two arguments, the following steps are taken:</p>
 72 |     <emu-alg>
 73 |       1. Let _O_ be ? ToObject(*this* value).
 74 |       1. Let _len_ be ? LengthOfArrayLike(_O_).
 75 |       1. If IsCallable(_callbackfn_) is *false*, throw a *TypeError* exception.
 76 |       1. Let _k_ be 0.
 77 |       1. Let _groups_ be a new empty List.
 78 |       1. Repeat, while _k_ &lt; _len_
 79 |         1. Let _Pk_ be ! ToString(𝔽(_k_)).
 80 |         1. Let _kValue_ be ? Get(_O_, _Pk_).
 81 |         1. Let _key_ be ? Call(_callbackfn_, _thisArg_, &laquo; _kValue_, 𝔽(_k_), _O_ &raquo;).
 82 |         1. If _key_ is *-0*<sub>𝔽</sub>, set _key_ to *+0*<sub>𝔽</sub>.
 83 |         1. Perform ! AddValueToKeyedGroup(_groups_, _key_, _kValue_).
 84 |         1. Set _k_ to _k_ + 1.
 85 |       1. Let _map_ be ! Construct(%Map%).
 86 |       1. For each Record { [[Key]], [[Elements]] } _g_ of _groups_, do
 87 |         1. Let _elements_ be ! CreateArrayFromList(_g_.[[Elements]]).
 88 |         1. Let _entry_ be the Record { [[Key]]: _g_.[[Key]], [[Value]]: _elements_ }.
 89 |         1. Append _entry_ as the last element of _map_.[[MapData]].
 90 |       1. Return _map_.
 91 |     </emu-alg>
 92 |     <emu-note>
 93 |       <p>The `groupBy` function is intentionally generic; it does not require that its *this* value be an Array object. Therefore it can be transferred to other kinds of objects for use as a method.</p>
 94 |     </emu-note>
 95 |   </emu-clause>
 96 | 
 97 |   <emu-clause id="sec-add-value-to-keyed-group" type="abstract operation">
 98 |     <h1>
 99 |       AddValueToKeyedGroup (
100 |         _groups_: a List of Records that have [[Key]] and [[Elements]] fields,
101 |         _key_: an ECMAScript language value,
102 |         _value_: an ECMAScript language value,
103 |       )
104 |     </h1>
105 |     <emu-alg>
106 |         1. If _groups_ contains a Record _g_ such that ! SameValueZero(_g_.[[Key]], _key_) is *true*, then
107 |           1. Assert: exactly one element of _groups_ meets this criteria.
108 |           1. Append _value_ as the last element of _g_.[[Elements]].
109 |         1. Else,
110 |           1. Let _group_ be the Record { [[Key]]: _key_, [[Elements]]: &laquo; _value_ &raquo; }.
111 |           1. Append _group_ as the last element of _groups_.
112 |     </emu-alg>
113 |   </emu-clause>
114 |   </ins>
115 | </emu-clause>
116 | 


--------------------------------------------------------------------------------