├── .editorconfig ├── .gitattributes ├── .github └── workflows │ └── main.yml ├── .gitignore ├── .npmrc ├── index.d.ts ├── index.js ├── license ├── package.json ├── readme.md └── test.js /.editorconfig: -------------------------------------------------------------------------------- 1 | root = true 2 | 3 | [*] 4 | indent_style = tab 5 | end_of_line = lf 6 | charset = utf-8 7 | trim_trailing_whitespace = true 8 | insert_final_newline = true 9 | 10 | [*.yml] 11 | indent_style = space 12 | indent_size = 2 13 | -------------------------------------------------------------------------------- /.gitattributes: -------------------------------------------------------------------------------- 1 | * text=auto eol=lf 2 | -------------------------------------------------------------------------------- /.github/workflows/main.yml: -------------------------------------------------------------------------------- 1 | name: CI 2 | on: 3 | - push 4 | - pull_request 5 | jobs: 6 | test: 7 | name: Node.js ${{ matrix.node-version }} 8 | runs-on: ubuntu-latest 9 | strategy: 10 | fail-fast: false 11 | matrix: 12 | node-version: 13 | - 22 14 | - 18 15 | steps: 16 | - uses: actions/checkout@v4 17 | - uses: actions/setup-node@v4 18 | with: 19 | node-version: ${{ matrix.node-version }} 20 | - run: npm install 21 | - run: npm test 22 | -------------------------------------------------------------------------------- /.gitignore: -------------------------------------------------------------------------------- 1 | node_modules 2 | yarn.lock 3 | -------------------------------------------------------------------------------- /.npmrc: -------------------------------------------------------------------------------- 1 | package-lock=false 2 | -------------------------------------------------------------------------------- /index.d.ts: -------------------------------------------------------------------------------- 1 | /** 2 | Returns a new array that is rotated by the given number of steps. 3 | 4 | @param array - The array to rotate. 5 | @param steps - The number of steps to rotate. Can be negative. 6 | 7 | @example 8 | ``` 9 | import toRotated from 'to-rotated'; 10 | 11 | console.log(toRotated([1, 2, 3, 4, 5], 2)); 12 | //=> [4, 5, 1, 2, 3] 13 | 14 | console.log(toRotated([1, 2, 3, 4, 5], -2)); 15 | //=> [3, 4, 5, 1, 2] 16 | ``` 17 | */ 18 | export default function toRotated(array: readonly T[], steps: number): T[]; 19 | -------------------------------------------------------------------------------- /index.js: -------------------------------------------------------------------------------- 1 | export default function toRotated(array, steps) { 2 | if (!Array.isArray(array)) { 3 | throw new TypeError(`Expected an array, got \`${typeof array}\`.`); 4 | } 5 | 6 | if (!Number.isSafeInteger(steps)) { 7 | throw new TypeError(`The \`steps\` parameter must be an integer, got ${steps}.`); 8 | } 9 | 10 | const {length} = array; 11 | if (length === 0) { 12 | return [...array]; 13 | } 14 | 15 | const normalizedSteps = ((steps % length) + length) % length; 16 | if (normalizedSteps === 0) { 17 | return [...array]; 18 | } 19 | 20 | return [ 21 | ...array.slice(-normalizedSteps), 22 | ...array.slice(0, -normalizedSteps), 23 | ]; 24 | } 25 | -------------------------------------------------------------------------------- /license: -------------------------------------------------------------------------------- 1 | MIT License 2 | 3 | Copyright (c) Sindre Sorhus (https://sindresorhus.com) 4 | 5 | Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: 6 | 7 | The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. 8 | 9 | THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. 10 | -------------------------------------------------------------------------------- /package.json: -------------------------------------------------------------------------------- 1 | { 2 | "name": "to-rotated", 3 | "version": "1.0.0", 4 | "description": "Rotate an array by a given number of steps", 5 | "license": "MIT", 6 | "repository": "sindresorhus/to-rotated", 7 | "funding": "https://github.com/sponsors/sindresorhus", 8 | "author": { 9 | "name": "Sindre Sorhus", 10 | "email": "sindresorhus@gmail.com", 11 | "url": "https://sindresorhus.com" 12 | }, 13 | "type": "module", 14 | "exports": { 15 | "types": "./index.d.ts", 16 | "default": "./index.js" 17 | }, 18 | "sideEffects": false, 19 | "engines": { 20 | "node": ">=18" 21 | }, 22 | "scripts": { 23 | "test": "xo && ava" 24 | }, 25 | "files": [ 26 | "index.js", 27 | "index.d.ts" 28 | ], 29 | "keywords": [ 30 | "array", 31 | "rotate", 32 | "rotation", 33 | "rotated", 34 | "shift", 35 | "immutable", 36 | "steps", 37 | "cycle", 38 | "cycling", 39 | "cycled", 40 | "move" 41 | ], 42 | "devDependencies": { 43 | "ava": "^6.1.3", 44 | "xo": "^0.58.0" 45 | } 46 | } 47 | -------------------------------------------------------------------------------- /readme.md: -------------------------------------------------------------------------------- 1 | # to-rotated 2 | 3 | > Rotate an array by a given number of steps 4 | 5 | Array rotation shifts the elements left or right by a certain number of steps. Elements that move past the end reappear at the beginning. For example, rotating `[1, 2, 3, 4, 5]` by 2 steps to the right results in `[4, 5, 1, 2, 3]`. 6 | 7 | ## Install 8 | 9 | ```sh 10 | npm install to-rotated 11 | ``` 12 | 13 | ## Usage 14 | 15 | ```js 16 | import toRotated from 'to-rotated'; 17 | 18 | console.log(toRotated([1, 2, 3, 4, 5], 2)); 19 | //=> [4, 5, 1, 2, 3] 20 | 21 | console.log(toRotated([1, 2, 3, 4, 5], -2)); 22 | //=> [3, 4, 5, 1, 2] 23 | ``` 24 | 25 | ## API 26 | 27 | ### toRotated(array, steps) 28 | 29 | Returns a new array that is rotated by the given number of steps. 30 | -------------------------------------------------------------------------------- /test.js: -------------------------------------------------------------------------------- 1 | import test from 'ava'; 2 | import toRotated from './index.js'; 3 | 4 | test('rotate array by positive steps', t => { 5 | t.deepEqual(toRotated([1, 2, 3, 4, 5], 2), [4, 5, 1, 2, 3]); 6 | }); 7 | 8 | test('rotate array by negative steps', t => { 9 | t.deepEqual(toRotated([1, 2, 3, 4, 5], -2), [3, 4, 5, 1, 2]); 10 | }); 11 | 12 | test('rotate array by zero steps', t => { 13 | t.deepEqual(toRotated([1, 2, 3, 4, 5], 0), [1, 2, 3, 4, 5]); 14 | }); 15 | 16 | test('rotate array by length of the array', t => { 17 | t.deepEqual(toRotated([1, 2, 3, 4, 5], 5), [1, 2, 3, 4, 5]); 18 | }); 19 | 20 | test('rotate array by negative length of the array', t => { 21 | t.deepEqual(toRotated([1, 2, 3, 4, 5], -5), [1, 2, 3, 4, 5]); 22 | }); 23 | 24 | test('rotate array by more than length of the array', t => { 25 | t.deepEqual(toRotated([1, 2, 3, 4, 5], 7), [4, 5, 1, 2, 3]); 26 | }); 27 | --------------------------------------------------------------------------------