87 lines
2.9 KiB
Markdown
87 lines
2.9 KiB
Markdown
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<a href="http://promises-aplus.github.com/promises-spec">
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<img src="http://promises-aplus.github.com/promises-spec/assets/logo-small.png"
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align="right" alt="Promises/A+ logo" />
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</a>
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# Promise Polyfill
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[![travis][travis-image]][travis-url]
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[travis-image]: https://img.shields.io/travis/taylorhakes/promise-polyfill.svg?style=flat
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[travis-url]: https://travis-ci.org/taylorhakes/promise-polyfill
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Lightweight ES6 Promise polyfill for the browser and node. Adheres closely to the spec. It is a perfect polyfill IE, Firefox or any other browser that does not support native promises.
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For API information about Promises, please check out this article [HTML5Rocks article](http://www.html5rocks.com/en/tutorials/es6/promises/).
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It is extremely lightweight. ***< 1kb Gzipped***
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## Browser Support
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IE8+, Chrome, Firefox, IOS 4+, Safari 5+, Opera
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### NPM Use
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```
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npm install promise-polyfill --save-exact
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```
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### Bower Use
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```
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bower install promise-polyfill
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```
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## Downloads
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- [Promise](https://raw.github.com/taylorhakes/promise-polyfill/master/promise.js)
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- [Promise-min](https://raw.github.com/taylorhakes/promise-polyfill/master/promise.min.js)
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## Simple use
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```js
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var prom = new Promise(function(resolve, reject) {
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// do a thing, possibly async, then…
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if (/* everything turned out fine */) {
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resolve("Stuff worked!");
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} else {
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reject(new Error("It broke"));
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}
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});
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prom.then(function(result) {
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// Do something when async done
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});
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```
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## Deprecations
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- `Promise._setImmediateFn(<immediateFn>)` has been deprecated. Use `Promise._immediateFn = <immediateFn>;` instead.
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- `Promise._setUnhandledRejectionFn(<rejectionFn>)` has been deprecated. Use `Promise._unhandledRejectionFn = <rejectionFn>` instead.
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These functions will be removed in the next major version.
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## Performance
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By default promise-polyfill uses `setImmediate`, but falls back to `setTimeout` for executing asynchronously. If a browser does not support `setImmediate` (IE/Edge are the only browsers with setImmediate), you may see performance issues.
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Use a `setImmediate` polyfill to fix this issue. [setAsap](https://github.com/taylorhakes/setAsap) or [setImmediate](https://github.com/YuzuJS/setImmediate) work well.
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If you polyfill `window.setImmediate` or use `Promise._immediateFn = yourImmediateFn` it will be used instead of `window.setTimeout`
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```
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npm install setasap --save
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```
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```js
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var Promise = require('promise-polyfill');
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var setAsap = require('setasap');
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Promise._immediateFn = setAsap;
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```
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## Unhandled Rejections
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promise-polyfill will warn you about possibly unhandled rejections. It will show a console warning if a Promise is rejected, but no `.catch` is used. You can turn off this behavior by setting `Promise._setUnhandledRejectionFn(<rejectError>)`.
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If you would like to disable unhandled rejections. Use a noop like below.
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```js
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Promise._unhandledRejectionFn = function(rejectError) {};
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```
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## Testing
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```
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npm install
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npm test
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```
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## License
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MIT
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