# es5-shim ^{[![Version Badge][npm-version-svg]][package-url]} [![github actions][actions-image]][actions-url] [![coverage][codecov-image]][codecov-url] [![dependency status][deps-svg]][deps-url] [![dev dependency status][dev-deps-svg]][dev-deps-url] [![License][license-image]][license-url] [![Downloads][downloads-image]][downloads-url] [![npm badge][npm-badge-png]][package-url] `es5-shim.js` and `es5-shim.min.js` monkey-patch a JavaScript context to contain all EcmaScript 5 methods that can be faithfully emulated with a legacy JavaScript engine. **Note:** As `es5-shim.js` is designed to patch the native Javascript engine, it should be the library that is loaded first. `es5-sham.js` and `es5-sham.min.js` monkey-patch other ES5 methods as closely as possible. For these methods, as closely as possible to ES5 is not very close. Many of these shams are intended only to allow code to be written to ES5 without causing run-time errors in older engines. In many cases, this means that these shams cause many ES5 methods to silently fail. Decide carefully whether this is what you want. **Note:** `es5-sham.js` requires `es5-shim.js` to be able to work properly. ## Tests The tests are written with the Jasmine BDD test framework. To run the tests, navigate to /tests/ , or, simply `npm install` and `npm test`. ## Shims ### Complete tests ### * Array.prototype.every ([standalone shim](https://www.npmjs.com/package/array.prototype.every)) * Array.prototype.filter ([standalone shim](https://www.npmjs.com/package/array.prototype.filter)) * Array.prototype.forEach ([standalone shim](https://www.npmjs.com/package/array.prototype.foreach)) * Array.prototype.indexOf ([standalone shim](https://www.npmjs.com/package/array.prototype.indexof)) * Array.prototype.lastIndexOf ([standalone shim](https://www.npmjs.com/package/array.prototype.lastindexof)) * Array.prototype.map ([standalone shim](https://www.npmjs.com/package/array.prototype.map)) * Array.prototype.slice * Array.prototype.some ([standalone shim](https://www.npmjs.com/package/array.prototype.some)) * Array.prototype.sort * Array.prototype.reduce ([standalone shim](https://www.npmjs.com/package/array.prototype.reduce)) * Array.prototype.reduceRight ([standalone shim](https://www.npmjs.com/package/array.prototype.reduceright)) * Array.prototype.push ([standalone shim](https://www.npmjs.com/package/array.prototype.push)) * Array.prototype.join * Array.prototype.splice ([standalone shim](https://www.npmjs.com/package/array.prototype.splice)) * Array.isArray * Date.now * Date.prototype.toJSON * Function.prototype.bind * :warning: Caveat: the bound function has a prototype property. * :warning: Caveat: bound functions do not try too hard to keep you from manipulating their ``arguments`` and ``caller`` properties. * :warning: Caveat: bound functions don't have checks in ``call`` and ``apply`` to avoid executing as a constructor. * Number.prototype.toExponential ([standalone shim](https://www.npmjs.com/package/number.prototype.toexponential)) * Number.prototype.toFixed * Number.prototype.toPrecision * Object.keys ([standalone shim](https://www.npmjs.com/package/object-keys)) * String.prototype.split ([standalone shim](https://www.npmjs.com/package/string.prototype.split)) * String.prototype.trim ([standalone shim](https://www.npmjs.com/package/string.prototype.trim)) * String.prototype.lastIndexOf ([standalone shim](https://string.prototype.lastindexof)) * String.prototype.replace * Firefox (through v29) natively handles capturing groups incorrectly. * Date.parse (for ISO parsing) * Date.prototype.toISOString * parseInt * parseFloat * Error.prototype.toString * Error.prototype.name * Error.prototype.message * RegExp.prototype.toString ## Shams * :warning: Object.create For the case of simply "begetting" an object that inherits prototypically from another, this should work fine across legacy engines. :warning: The second argument is passed to Object.defineProperties which will probably fail either silently or with extreme prejudice. * :warning: Object.getPrototypeOf This will return "undefined" in some cases. It uses `__proto__` if it's available. Failing that, it uses constructor.prototype, which depends on the constructor property of the object's prototype having not been replaced. If your object was created like this, it won't work: function Foo() { } Foo.prototype = {}; Because the prototype reassignment destroys the constructor property. This will work for all objects that were created using `Object.create` implemented with this library. * :warning: Object.getOwnPropertyNames This method uses Object.keys, so it will not be accurate on legacy engines. * Object.isSealed Returns "false" in all legacy engines for all objects, which is conveniently guaranteed to be accurate. * Object.isFrozen Returns "false" in all legacy engines for all objects, which is conveniently guaranteed to be accurate. * Object.isExtensible Works like a charm, by trying very hard to extend the object then redacting the extension. ### May fail * :warning: Object.getOwnPropertyDescriptor The behavior of this shim does not conform to ES5. It should probably not be used at this time, until its behavior has been reviewed and been confirmed to be useful in legacy engines. * :warning: Object.defineProperty In the worst of circumstances, IE 8 provides a version of this method that only works on DOM objects. This sham will not be installed. The given version of `defineProperty` will throw an exception if used on non-DOM objects. In slightly better circumstances, this method will silently fail to set "writable", "enumerable", and "configurable" properties. Providing a getter or setter with "get" or "set" on a descriptor will silently fail on engines that lack "__defineGetter__" and "__defineSetter__", which include all versions of IE. https://github.com/es-shims/es5-shim/issues#issue/5 * :warning: Object.defineProperties This uses the Object.defineProperty shim. * Object.seal Silently fails on all legacy engines. This should be fine unless you are depending on the safety and security provisions of this method, which you cannot possibly obtain in legacy engines. * Object.freeze Silently fails on all legacy engines. This should be fine unless you are depending on the safety and security provisions of this method, which you cannot possibly obtain in legacy engines. * Object.preventExtensions Silently fails on all legacy engines. This should be fine unless you are depending on the safety and security provisions of this method, which you cannot possibly obtain in legacy engines. ### Example of applying ES compatibility shims in a browser project ```html ``` [package-url]: https://npmjs.org/package/es5-shim [npm-version-svg]: https://versionbadg.es/es-shims/es5-shim.svg [deps-svg]: https://david-dm.org/es-shims/es5-shim.svg [deps-url]: https://david-dm.org/es-shims/es5-shim [dev-deps-svg]: https://david-dm.org/es-shims/es5-shim/dev-status.svg [dev-deps-url]: https://david-dm.org/es-shims/es5-shim#info=devDependencies [npm-badge-png]: https://nodei.co/npm/es5-shim.png?downloads=true&stars=true [license-image]: https://img.shields.io/npm/l/es5-shim.svg [license-url]: LICENSE [downloads-image]: https://img.shields.io/npm/dm/es5-shim.svg [downloads-url]: https://npm-stat.com/charts.html?package=es5-shim [codecov-image]: https://codecov.io/gh/es-shims/es5-shim/branch/main/graphs/badge.svg [codecov-url]: https://app.codecov.io/gh/es-shims/es5-shim/ [actions-image]: https://img.shields.io/endpoint?url=https://github-actions-badge-u3jn4tfpocch.runkit.sh/es-shims/es5-shim [actions-url]: https://github.com/es-shims/es5-shim/actions

	Stars	Issues	Version	Updated	Created
airbnb-js-shims	123	0	2.2.1	4 years ago	8 years ago
es5-shim			4.6.7	2 years ago	13 years ago
es6-shim	3,119	33	0.35.8	a year ago	12 years ago
polyfill-library	650	57	4.8.0	10 months ago	6 years ago
polyfill-service	7,505	24	3.25.3	5 years ago	9 years ago

airbnb-js-shims vs es5-shim vs es6-shim vs polyfill-library vs polyfill-service

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