| 提交 | 用户 | 时间 | ||
| 1ac2bc | 1 | |
| 懒 | 2 | `es5-shim.js` and `es5-shim.min.js` monkey-patch a JavaScript context to |
| 3 | contain all EcmaScript 5 methods that can be faithfully emulated with a | |
| 4 | legacy JavaScript engine. | |
| 5 | ||
| 6 | `es5-sham.js` and `es5-sham.min.js` monkey-patch other ES5 methods as | |
| 7 | closely as possible. For these methods, as closely as possible to ES5 | |
| 8 | is not very close. Many of these shams are intended only to allow code | |
| 9 | to be written to ES5 without causing run-time errors in older engines. | |
| 10 | In many cases, this means that these shams cause many ES5 methods to | |
| 11 | silently fail. Decide carefully whether this is what you want. | |
| 12 | ||
| 13 | ||
| 14 | ## Tests | |
| 15 | ||
| 16 | The tests are written with the Jasmine BDD test framework. | |
| 17 | To run the tests, navigate to <root-folder>/tests/. | |
| 18 | ||
| 19 | In order to run against the shim-code, the tests attempt to kill the current | |
| 20 | implementation of the missing methods. This happens in <root-folder>/tests/helpers/h-kill.js. | |
| 21 | So in order to run the tests against the built-in methods, invalidate that file somehow | |
| 22 | (comment-out, delete the file, delete the script-tag, etc.). | |
| 23 | ||
| 24 | ## Shims | |
| 25 | ||
| 26 | ### Complete tests ### | |
| 27 | ||
| 28 | * Array.prototype.every | |
| 29 | * Array.prototype.filter | |
| 30 | * Array.prototype.forEach | |
| 31 | * Array.prototype.indexOf | |
| 32 | * Array.prototype.lastIndexOf | |
| 33 | * Array.prototype.map | |
| 34 | * Array.prototype.some | |
| 35 | * Array.prototype.reduce | |
| 36 | * Array.prototype.reduceRight | |
| 37 | * Array.isArray | |
| 38 | * Date.now | |
| 39 | * Date.prototype.toJSON | |
| 40 | * Function.prototype.bind | |
| 41 | * /!\ Caveat: the bound function's length is always 0. | |
| 42 | * /!\ Caveat: the bound function has a prototype property. | |
| 43 | * /!\ Caveat: bound functions do not try too hard to keep you | |
| 44 | from manipulating their ``arguments`` and ``caller`` properties. | |
| 45 | * /!\ Caveat: bound functions don't have checks in ``call`` and | |
| 46 | ``apply`` to avoid executing as a constructor. | |
| 47 | * Object.keys | |
| 48 | * String.prototype.trim | |
| 49 | ||
| 50 | ### Untested ### | |
| 51 | ||
| 52 | * Date.parse (for ISO parsing) | |
| 53 | * Date.prototype.toISOString | |
| 54 | ||
| 55 | ## Shams | |
| 56 | ||
| 57 | * /?\ Object.create | |
| 58 | ||
| 59 | For the case of simply "begetting" an object that | |
| 60 | inherits prototypically from another, this should work | |
| 61 | fine across legacy engines. | |
| 62 | ||
| 63 | /!\ Object.create(null) will work only in browsers that | |
| 64 | support prototype assignment. This creates an object | |
| 65 | that does not have any properties inherited from | |
| 66 | Object.prototype. It will silently fail otherwise. | |
| 67 | ||
| 68 | /!\ The second argument is passed to | |
| 69 | Object.defineProperties which will probably fail | |
| 70 | silently. | |
| 71 | ||
| 72 | * /?\ Object.getPrototypeOf | |
| 73 | ||
| 74 | This will return "undefined" in some cases. It uses | |
| 75 | __proto__ if it's available. Failing that, it uses | |
| 76 | constructor.prototype, which depends on the constructor | |
| 77 | property of the object's prototype having not been | |
| 78 | replaced. If your object was created like this, it | |
| 79 | won't work: | |
| 80 | ||
| 81 | function Foo() { | |
| 82 | } | |
| 83 | Foo.prototype = {}; | |
| 84 | ||
| 85 | Because the prototype reassignment destroys the | |
| 86 | constructor property. | |
| 87 | ||
| 88 | This will work for all objects that were created using | |
| 89 | `Object.create` implemented with this library. | |
| 90 | ||
| 91 | * /!\ Object.getOwnPropertyNames | |
| 92 | ||
| 93 | This method uses Object.keys, so it will not be accurate | |
| 94 | on legacy engines. | |
| 95 | ||
| 96 | * Object.isSealed | |
| 97 | ||
| 98 | Returns "false" in all legacy engines for all objects, | |
| 99 | which is conveniently guaranteed to be accurate. | |
| 100 | ||
| 101 | * Object.isFrozen | |
| 102 | ||
| 103 | Returns "false" in all legacy engines for all objects, | |
| 104 | which is conveniently guaranteed to be accurate. | |
| 105 | ||
| 106 | * Object.isExtensible | |
| 107 | ||
| 108 | Works like a charm, by trying very hard to extend the | |
| 109 | object then redacting the extension. | |
| 110 | ||
| 111 | ### Fail silently | |
| 112 | ||
| 113 | * /!\ Object.getOwnPropertyDescriptor | |
| 114 | ||
| 115 | The behavior of this shim does not conform to ES5. It | |
| 116 | should probably not be used at this time, until its | |
| 117 | behavior has been reviewed and been confirmed to be | |
| 118 | useful in legacy engines. | |
| 119 | ||
| 120 | * /!\ Object.defineProperty | |
| 121 | ||
| 122 | This method will silently fail to set "writable", | |
| 123 | "enumerable", and "configurable" properties. | |
| 124 | ||
| 125 | Providing a getter or setter with "get" or "set" on a | |
| 126 | descriptor will silently fail on engines that lack | |
| 127 | "__defineGetter__" and "__defineSetter__", which include | |
| 128 | all versions of IE up to version 8 so far. | |
| 129 | ||
| 130 | IE 8 provides a version of this method but it only works | |
| 131 | on DOM objects. Thus, the shim will not get installed | |
| 132 | and attempts to set "value" properties will fail | |
| 133 | silently on non-DOM objects. | |
| 134 | ||
| 135 | https://github.com/kriskowal/es5-shim/issues#issue/5 | |
| 136 | ||
| 137 | * /!\ Object.defineProperties | |
| 138 | ||
| 139 | This uses the Object.defineProperty shim | |
| 140 | ||
| 141 | * Object.seal | |
| 142 | ||
| 143 | Silently fails on all legacy engines. This should be | |
| 144 | fine unless you are depending on the safety and security | |
| 145 | provisions of this method, which you cannot possibly | |
| 146 | obtain in legacy engines. | |
| 147 | ||
| 148 | * Object.freeze | |
| 149 | ||
| 150 | Silently fails on all legacy engines. This should be | |
| 151 | fine unless you are depending on the safety and security | |
| 152 | provisions of this method, which you cannot possibly | |
| 153 | obtain in legacy engines. | |
| 154 | ||
| 155 | * Object.preventExtensions | |
| 156 | ||
| 157 | Silently fails on all legacy engines. This should be | |
| 158 | fine unless you are depending on the safety and security | |
| 159 | provisions of this method, which you cannot possibly | |
| 160 | obtain in legacy engines. | |
| 161 | ||
