From 0a621ccc12348159e049c3d03b02ded7f027a92f Mon Sep 17 00:00:00 2001 From: Mathias Bynens Date: Tue, 17 Dec 2013 22:09:49 +0100 Subject: [PATCH] Improve `String.prototype.startsWith` polyfill --- bin/traceur.js | 19 ++- src/runtime/runtime.js | 22 ++- test/feature/StringExtras/StartsWith.js | 206 +++++++++++++++++++++++- 3 files changed, 239 insertions(+), 8 deletions(-) diff --git a/bin/traceur.js b/bin/traceur.js index 74301448d..4fe9d1163 100644 --- a/bin/traceur.js +++ b/bin/traceur.js @@ -13,6 +13,7 @@ var $getOwnPropertyNames = $Object.getOwnPropertyNames; var $getPrototypeOf = $Object.getPrototypeOf; var $hasOwnProperty = $Object.prototype.hasOwnProperty; + var $toString = $Object.prototype.toString; function nonEnum(value) { return { configurable: true, @@ -23,9 +24,23 @@ } var method = nonEnum; function polyfillString(String) { + var $indexOf = String.prototype.indexOf; $defineProperties(String.prototype, { - startsWith: method(function(s) { - return this.lastIndexOf(s, 0) === 0; + startsWith: method(function(search) { + if (this == null || $toString.call(search) == '[object RegExp]') { + throw TypeError(); + } + var string = String(this); + var stringLength = string.length; + var searchString = String(search); + var searchLength = searchString.length; + var position = arguments[1]; + var pos = position ? Number(position): 0; + if (isNaN(pos)) { + pos = 0; + } + var start = Math.min(Math.max(pos, 0), stringLength); + return $indexOf.call(string, searchString, pos) == start; }), endsWith: method(function(s) { var t = String(s); diff --git a/src/runtime/runtime.js b/src/runtime/runtime.js index 8f2c9688b..a28142c08 100644 --- a/src/runtime/runtime.js +++ b/src/runtime/runtime.js @@ -33,6 +33,7 @@ var $getOwnPropertyNames = $Object.getOwnPropertyNames; var $getPrototypeOf = $Object.getPrototypeOf; var $hasOwnProperty = $Object.prototype.hasOwnProperty; + var $toString = $Object.prototype.toString; function nonEnum(value) { return { @@ -46,11 +47,28 @@ var method = nonEnum; function polyfillString(String) { + var $indexOf = String.prototype.indexOf; // Harmony String Extras // http://wiki.ecmascript.org/doku.php?id=harmony:string_extras $defineProperties(String.prototype, { - startsWith: method(function(s) { - return this.lastIndexOf(s, 0) === 0; + // http://people.mozilla.org/~jorendorff/es6-draft.html#sec-string.prototype.startswith + startsWith: method(function(search) { + /*! http://mths.be/startswith v0.1.0 by @mathias */ + if (this == null || $toString.call(search) == '[object RegExp]') { + throw TypeError(); + } + var string = String(this); + var stringLength = string.length; + var searchString = String(search); + var searchLength = searchString.length; + var position = arguments[1]; + // `ToInteger` + var pos = position ? Number(position) : 0; + if (isNaN(pos)) { + pos = 0; + } + var start = Math.min(Math.max(pos, 0), stringLength); + return $indexOf.call(string, searchString, pos) == start; }), endsWith: method(function(s) { var t = String(s); diff --git a/test/feature/StringExtras/StartsWith.js b/test/feature/StringExtras/StartsWith.js index d4b03c046..bb24f5e9e 100644 --- a/test/feature/StringExtras/StartsWith.js +++ b/test/feature/StringExtras/StartsWith.js @@ -1,4 +1,202 @@ -assert.isTrue('Hello World!'.startsWith('Hello ')); -assert.isFalse('Hello World!'.startsWith('World!')); -assert.isTrue('Hello World!'.startsWith('')); -assert.isFalse('Hello World!'.startsWith('h')); +assert.equal(String.prototype.startsWith.length, 1); + +assert.equal('undefined'.startsWith(), true); +assert.equal('undefined'.startsWith(undefined), true); +assert.equal('undefined'.startsWith(null), false); +assert.equal('null'.startsWith(), false); +assert.equal('null'.startsWith(undefined), false); +assert.equal('null'.startsWith(null), true); + +assert.equal('abc'.startsWith(), false); +assert.equal('abc'.startsWith(''), true); +assert.equal('abc'.startsWith('\0'), false); +assert.equal('abc'.startsWith('a'), true); +assert.equal('abc'.startsWith('b'), false); +assert.equal('abc'.startsWith('ab'), true); +assert.equal('abc'.startsWith('bc'), false); +assert.equal('abc'.startsWith('abc'), true); +assert.equal('abc'.startsWith('bcd'), false); +assert.equal('abc'.startsWith('abcd'), false); +assert.equal('abc'.startsWith('bcde'), false); + +assert.equal('abc'.startsWith('', NaN), true); +assert.equal('abc'.startsWith('\0', NaN), false); +assert.equal('abc'.startsWith('a', NaN), true); +assert.equal('abc'.startsWith('b', NaN), false); +assert.equal('abc'.startsWith('ab', NaN), true); +assert.equal('abc'.startsWith('bc', NaN), false); +assert.equal('abc'.startsWith('abc', NaN), true); +assert.equal('abc'.startsWith('bcd', NaN), false); +assert.equal('abc'.startsWith('abcd', NaN), false); +assert.equal('abc'.startsWith('bcde', NaN), false); + +assert.equal('abc'.startsWith('', false), true); +assert.equal('abc'.startsWith('\0', false), false); +assert.equal('abc'.startsWith('a', false), true); +assert.equal('abc'.startsWith('b', false), false); +assert.equal('abc'.startsWith('ab', false), true); +assert.equal('abc'.startsWith('bc', false), false); +assert.equal('abc'.startsWith('abc', false), true); +assert.equal('abc'.startsWith('bcd', false), false); +assert.equal('abc'.startsWith('abcd', false), false); +assert.equal('abc'.startsWith('bcde', false), false); + +assert.equal('abc'.startsWith('', undefined), true); +assert.equal('abc'.startsWith('\0', undefined), false); +assert.equal('abc'.startsWith('a', undefined), true); +assert.equal('abc'.startsWith('b', undefined), false); +assert.equal('abc'.startsWith('ab', undefined), true); +assert.equal('abc'.startsWith('bc', undefined), false); +assert.equal('abc'.startsWith('abc', undefined), true); +assert.equal('abc'.startsWith('bcd', undefined), false); +assert.equal('abc'.startsWith('abcd', undefined), false); +assert.equal('abc'.startsWith('bcde', undefined), false); + +assert.equal('abc'.startsWith('', null), true); +assert.equal('abc'.startsWith('\0', null), false); +assert.equal('abc'.startsWith('a', null), true); +assert.equal('abc'.startsWith('b', null), false); +assert.equal('abc'.startsWith('ab', null), true); +assert.equal('abc'.startsWith('bc', null), false); +assert.equal('abc'.startsWith('abc', null), true); +assert.equal('abc'.startsWith('bcd', null), false); +assert.equal('abc'.startsWith('abcd', null), false); +assert.equal('abc'.startsWith('bcde', null), false); + +assert.equal('abc'.startsWith('', -Infinity), true); +assert.equal('abc'.startsWith('\0', -Infinity), false); +assert.equal('abc'.startsWith('a', -Infinity), true); +assert.equal('abc'.startsWith('b', -Infinity), false); +assert.equal('abc'.startsWith('ab', -Infinity), true); +assert.equal('abc'.startsWith('bc', -Infinity), false); +assert.equal('abc'.startsWith('abc', -Infinity), true); +assert.equal('abc'.startsWith('bcd', -Infinity), false); +assert.equal('abc'.startsWith('abcd', -Infinity), false); +assert.equal('abc'.startsWith('bcde', -Infinity), false); + +assert.equal('abc'.startsWith('', -1), true); +assert.equal('abc'.startsWith('\0', -1), false); +assert.equal('abc'.startsWith('a', -1), true); +assert.equal('abc'.startsWith('b', -1), false); +assert.equal('abc'.startsWith('ab', -1), true); +assert.equal('abc'.startsWith('bc', -1), false); +assert.equal('abc'.startsWith('abc', -1), true); +assert.equal('abc'.startsWith('bcd', -1), false); +assert.equal('abc'.startsWith('abcd', -1), false); +assert.equal('abc'.startsWith('bcde', -1), false); + +assert.equal('abc'.startsWith('', -0), true); +assert.equal('abc'.startsWith('\0', -0), false); +assert.equal('abc'.startsWith('a', -0), true); +assert.equal('abc'.startsWith('b', -0), false); +assert.equal('abc'.startsWith('ab', -0), true); +assert.equal('abc'.startsWith('bc', -0), false); +assert.equal('abc'.startsWith('abc', -0), true); +assert.equal('abc'.startsWith('bcd', -0), false); +assert.equal('abc'.startsWith('abcd', -0), false); +assert.equal('abc'.startsWith('bcde', -0), false); + +assert.equal('abc'.startsWith('', +0), true); +assert.equal('abc'.startsWith('\0', +0), false); +assert.equal('abc'.startsWith('a', +0), true); +assert.equal('abc'.startsWith('b', +0), false); +assert.equal('abc'.startsWith('ab', +0), true); +assert.equal('abc'.startsWith('bc', +0), false); +assert.equal('abc'.startsWith('abc', +0), true); +assert.equal('abc'.startsWith('bcd', +0), false); +assert.equal('abc'.startsWith('abcd', +0), false); +assert.equal('abc'.startsWith('bcde', +0), false); + +assert.equal('abc'.startsWith('', 1), true); +assert.equal('abc'.startsWith('\0', 1), false); +assert.equal('abc'.startsWith('a', 1), false); +assert.equal('abc'.startsWith('b', 1), true); +assert.equal('abc'.startsWith('ab', 1), false); +assert.equal('abc'.startsWith('bc', 1), true); +assert.equal('abc'.startsWith('abc', 1), false); +assert.equal('abc'.startsWith('bcd', 1), false); +assert.equal('abc'.startsWith('abcd', 1), false); +assert.equal('abc'.startsWith('bcde', 1), false); + +assert.equal('abc'.startsWith('', +Infinity), true); +assert.equal('abc'.startsWith('\0', +Infinity), false); +assert.equal('abc'.startsWith('a', +Infinity), false); +assert.equal('abc'.startsWith('b', +Infinity), false); +assert.equal('abc'.startsWith('ab', +Infinity), false); +assert.equal('abc'.startsWith('bc', +Infinity), false); +assert.equal('abc'.startsWith('abc', +Infinity), false); +assert.equal('abc'.startsWith('bcd', +Infinity), false); +assert.equal('abc'.startsWith('abcd', +Infinity), false); +assert.equal('abc'.startsWith('bcde', +Infinity), false); + +assert.equal('abc'.startsWith('', true), true); +assert.equal('abc'.startsWith('\0', true), false); +assert.equal('abc'.startsWith('a', true), false); +assert.equal('abc'.startsWith('b', true), true); +assert.equal('abc'.startsWith('ab', true), false); +assert.equal('abc'.startsWith('bc', true), true); +assert.equal('abc'.startsWith('abc', true), false); +assert.equal('abc'.startsWith('bcd', true), false); +assert.equal('abc'.startsWith('abcd', true), false); +assert.equal('abc'.startsWith('bcde', true), false); + +assert.equal('abc'.startsWith('', 'x'), true); +assert.equal('abc'.startsWith('\0', 'x'), false); +assert.equal('abc'.startsWith('a', 'x'), true); +assert.equal('abc'.startsWith('b', 'x'), false); +assert.equal('abc'.startsWith('ab', 'x'), true); +assert.equal('abc'.startsWith('bc', 'x'), false); +assert.equal('abc'.startsWith('abc', 'x'), true); +assert.equal('abc'.startsWith('bcd', 'x'), false); +assert.equal('abc'.startsWith('abcd', 'x'), false); +assert.equal('abc'.startsWith('bcde', 'x'), false); + +assert.equal('[a-z]+(bar)?'.startsWith('[a-z]+'), true); +assertThrows(function() { '[a-z]+(bar)?'.startsWith(/[a-z]+/); }, TypeError); +assert.equal('[a-z]+(bar)?'.startsWith('(bar)?', 6), true); +assertThrows(function() { '[a-z]+(bar)?'.startsWith(/(bar)?/); }, TypeError); +assertThrows(function() { '[a-z]+/(bar)?/'.startsWith(/(bar)?/); }, TypeError); + +// http://mathiasbynens.be/notes/javascript-unicode#poo-test +var string = 'I\xF1t\xEBrn\xE2ti\xF4n\xE0liz\xE6ti\xF8n\u2603\uD83D\uDCA9'; +assert.equal(string.startsWith(''), true); +assert.equal(string.startsWith('\xF1t\xEBr'), false); +assert.equal(string.startsWith('\xF1t\xEBr', 1), true); +assert.equal(string.startsWith('\xE0liz\xE6'), false); +assert.equal(string.startsWith('\xE0liz\xE6', 11), true); +assert.equal(string.startsWith('\xF8n\u2603\uD83D\uDCA9'), false); +assert.equal(string.startsWith('\xF8n\u2603\uD83D\uDCA9', 18), true); +assert.equal(string.startsWith('\u2603'), false); +assert.equal(string.startsWith('\u2603', 20), true); +assert.equal(string.startsWith('\uD83D\uDCA9'), false); +assert.equal(string.startsWith('\uD83D\uDCA9', 21), true); + +assertThrows(function() { String.prototype.startsWith.call(undefined); }, TypeError); +assertThrows(function() { String.prototype.startsWith.call(undefined, 'b'); }, TypeError); +assertThrows(function() { String.prototype.startsWith.call(undefined, 'b', 4); }, TypeError); +assertThrows(function() { String.prototype.startsWith.call(null); }, TypeError); +assertThrows(function() { String.prototype.startsWith.call(null, 'b'); }, TypeError); +assertThrows(function() { String.prototype.startsWith.call(null, 'b', 4); }, TypeError); +assert.equal(String.prototype.startsWith.call(42, '2'), false); +assert.equal(String.prototype.startsWith.call(42, '4'), true); +assert.equal(String.prototype.startsWith.call(42, 'b', 4), false); +assert.equal(String.prototype.startsWith.call(42, '2', 1), true); +assert.equal(String.prototype.startsWith.call(42, '2', 4), false); +assert.equal(String.prototype.startsWith.call({ 'toString': function() { return 'abc'; } }, 'b', 0), false); +assert.equal(String.prototype.startsWith.call({ 'toString': function() { return 'abc'; } }, 'b', 1), true); +assert.equal(String.prototype.startsWith.call({ 'toString': function() { return 'abc'; } }, 'b', 2), false); + +assertThrows(function() { String.prototype.startsWith.apply(undefined); }, TypeError); +assertThrows(function() { String.prototype.startsWith.apply(undefined, ['b']); }, TypeError); +assertThrows(function() { String.prototype.startsWith.apply(undefined, ['b', 4]); }, TypeError); +assertThrows(function() { String.prototype.startsWith.apply(null); }, TypeError); +assertThrows(function() { String.prototype.startsWith.apply(null, ['b']); }, TypeError); +assertThrows(function() { String.prototype.startsWith.apply(null, ['b', 4]); }, TypeError); +assert.equal(String.prototype.startsWith.apply(42, ['2']), false); +assert.equal(String.prototype.startsWith.apply(42, ['4']), true); +assert.equal(String.prototype.startsWith.apply(42, ['b', 4]), false); +assert.equal(String.prototype.startsWith.apply(42, ['2', 1]), true); +assert.equal(String.prototype.startsWith.apply(42, ['2', 4]), false); +assert.equal(String.prototype.startsWith.apply({ 'toString': function() { return 'abc'; } }, ['b', 0]), false); +assert.equal(String.prototype.startsWith.apply({ 'toString': function() { return 'abc'; } }, ['b', 1]), true); +assert.equal(String.prototype.startsWith.apply({ 'toString': function() { return 'abc'; } }, ['b', 2]), false);