├── .gitignore
├── README.md
├── build.sh
├── package.json
└── spec.emu
/.gitignore:
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1 | node_modules/
2 | npm-debug.log
3 |
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/README.md:
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1 | # String.prototype.trimStart / String.prototype.trimEnd
2 |
3 | ECMAScript proposal, specs, tests, and reference implementation for String.prototype.trimStart/trimEnd (plus **trimLeft/trimRight**).
4 |
5 | **Stage 4**
6 |
7 | This proposal is complete and already merged into [ECMA262 specification](https://tc39.es/ecma262/). See the specification text here.
8 |
9 | ## Rationale
10 | ES5 standardized `String.prototype.trim`. All major engines have also implemented corresponding `trimLeft` and `trimRight` functions - without any standard specification.
11 | For consistency with `padStart`/`padEnd` we propose `trimStart` and `trimEnd` and `trimLeft`/`trimRight` as aliases required for web compatibility.
12 |
13 | ## Specification
14 | You can view the spec in [ecmarkup](spec.emu) or rendered as [HTML](https://tc39.github.io/proposal-string-left-right-trim/).
15 |
16 | ## Naming / Aliasing
17 | For consistency with `padStart`/`padEnd` the standard functions will be `trimStart` and `trimEnd`, however for web compatilibity `trimLeft` will alias `trimStart` and `trimRight` will alias `trimEnd`. This means `String.prototype.trimRight.name` will change from `"trimRight"` to `"trimEnd"` in most engines. The spec author does not expect this to cause any breakage.
18 |
19 | ## Test262 Coverage
20 |
21 | [PR open](https://github.com/tc39/test262/pull/1246)
22 |
23 | ## Status of This Proposal
24 |
25 | This initial proposal was drafted by [@sebmarkbage](https://github.com/sebmarkbage) and the updated spec was drafted by [@evilpie](https://github.com/evilpie/) with input from [@ljharb](https://github.com/ljharb).
26 |
27 | This proposal is currently at [stage 4](https://github.com/tc39/ecma262) of the [process](https://tc39.github.io/process-document/).
28 |
29 | Designated TC39 reviewers: Jordan Harband + Daniel Ehrenberg
30 |
31 | ## Implementations
32 |
33 | - [V8](https://bugs.chromium.org/p/v8/issues/detail?id=6530), in Chrome 66+
34 | - [SpiderMonkey](https://bugzilla.mozilla.org/show_bug.cgi?id=1434007#c12), in Firefox 61+
35 | - [JSC](https://bugs.webkit.org/show_bug.cgi?id=26590), in Safari 12+
36 | - [ChakraCore](https://github.com/Microsoft/ChakraCore/pull/5693)
37 |
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/build.sh:
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1 | #!/bin/sh
2 |
3 | set -e
4 |
5 | BUILD_DIR=`mktemp -dt ecmascript-string-left-right` || exit 1
6 | trap "rm -rf $BUILD_DIR" EXIT
7 | mkdir "$BUILD_DIR/out"
8 |
9 | ./node_modules/.bin/ecmarkup \
10 | spec.emu \
11 | "$BUILD_DIR/out/index.html" \
12 | --js "$BUILD_DIR/out/spec.js" \
13 | --css "$BUILD_DIR/out/spec.css"
14 |
15 | # Replace gh-pages with a new commit without touching the working directory.
16 | GIT_WORK_TREE="$BUILD_DIR/out" GIT_INDEX_FILE="$BUILD_DIR/index" \
17 | git add index.html spec.js spec.css
18 | TREE=`GIT_WORK_TREE="$BUILD_DIR/out" GIT_INDEX_FILE="$BUILD_DIR/index" \
19 | git write-tree`
20 | COMMIT=`git commit-tree "$TREE" -m 'build gh-pages'`
21 | git branch -f gh-pages $COMMIT
22 |
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/package.json:
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1 | {
2 | "name": "ecmascript-string-left-right-trim",
3 | "repository": {
4 | "type": "git",
5 | "url": "git+https://github.com/sebmarkbage/ecmascript-string-left-right-trim"
6 | },
7 | "keywords": [
8 | "ecmascript",
9 | "string",
10 | "test262",
11 | "string.prototype.trimLeft",
12 | "string.prototype.trimRight",
13 | "string.prototype.trimStart",
14 | "string.prototype.trimEnd"
15 | ],
16 | "author": "Tom Schuster",
17 | "license": "MIT",
18 | "devDependencies": {
19 | "ecmarkup": "^3.2.6"
20 | }
21 | }
22 |
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/spec.emu:
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1 |
2 |
3 |
4 |
5 |
6 |
7 | title: String.prototype.trimStart/trimEnd (plus trimLeft/trimRight)
8 | stage: 3
9 | contributors: Sebastian Markbåge, Tom Schuster
10 |
11 |
12 |
13 |
String.prototype.trim ( )
14 |
The following steps are taken:
15 |
16 |
17 | 1. Let _O_ be ? RequireObjectCoercible(*this* value).
18 | 1. Let _S_ be ? ToString(_O_).
19 | 1. Let _T_ be a String value that is a copy of _S_ with both leading and trailing white space removed. The definition of white space is the union of |WhiteSpace| and |LineTerminator|. When determining whether a Unicode code point is in Unicode general category “Space_Separator” (“Zs”), code unit sequences are interpreted as UTF-16 encoded code point sequences as specified in .
20 | 1. Return _T_.
21 |
22 |
23 |
24 |
25 | 1. Let _S_ be *this* value.
26 | 1. Return ? TrimString(_S_, `"start+end"`).
27 |
28 |
29 |
30 |
The `trim` function is intentionally generic; it does not require that its *this* value be a String object. Therefore, it can be transferred to other kinds of objects for use as a method.
The `trimStart` function is intentionally generic; it does not require that its *this* value be a String object. Therefore, it can be transferred to other kinds of objects for use as a method.
The `trimEnd` function is intentionally generic; it does not require that its *this* value be a String object. Therefore, it can be transferred to other kinds of objects for use as a method.
The abstract operation TrimString is called with arguments _string_ and _where_, and interprets the String value _string_ as a sequence of UTF-16 encoded code points, as described in . It performs the following steps:
61 |
62 | 1. Let _str_ be ? RequireObjectCoercible(_string_).
63 | 1. Let _S_ be ? ToString(_str_).
64 | 1. If _where_ is `"start"`, let _T_ be a String value that is a copy of _S_ with leading white space removed.
65 | 1. Else if _where_ is `"end"`, let _T_ be a String value that is a copy of _S_ with trailing white space removed.
66 | 1. Else,
67 | 1. Assert: _where_ is `"start+end"`.
68 | 1. Let _T_ be a String value that is a copy of _S_ with both leading and trailing white space removed.
69 | 1. Return _T_.
70 |
71 |
The definition of white space is the union of |WhiteSpace| and |LineTerminator|. When determining whether a Unicode code point is in Unicode general category “Zs”, code unit sequences are interpreted as UTF-16 encoded code point sequences as specified in .
72 |
73 |
74 |
75 |
Additional ECMAScript Features for Web Browsers
76 |
77 |
78 |
String.prototype.trimLeft ( )
79 |
80 |
The property `trimStart` is preferred. The `trimLeft` property is provided principally for compatibility with old code. It is recommended that the `trimStart` property be used in new ECMAScript code.
81 |
82 |
The initial value of the `trimLeft` property is the same function object as the initial value of the `String.prototype.trimStart` property.
83 |
84 |
85 |
86 |
String.prototype.trimRight ( )
87 |
88 |
The property `trimEnd` is preferred. The `trimRight` property is provided principally for compatibility with old code. It is recommended that the `trimEnd` property be used in new ECMAScript code.
89 |
90 |
The initial value of the `trimRight` property is the same function object as the initial value of the `String.prototype.trimEnd` property.