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.
For API information about Promises, please check out this article HTML5Rocks article.
It is extremely lightweight. < 1kb Gzipped
IE8+, Chrome, Firefox, IOS 4+, Safari 5+, Opera
npm install promise-polyfill --save-exact
bower install promise-polyfill
<script src="https://cdn.jsdelivr.net/npm/promise-polyfill@7/dist/polyfill.min.js"></script>import Promise from 'promise-polyfill';then you can use like normal Promises
var prom = new Promise(function(resolve, reject) {
// do a thing, possibly async, then…
if (/* everything turned out fine */) {
resolve("Stuff worked!");
} else {
reject(new Error("It broke"));
}
});
prom.then(function(result) {
// Do something when async done
});If you would like to just polyfill, only if native doesn't exist.
import 'promise-polyfill/src/polyfill';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. Use a setImmediate polyfill to fix this issue.
setAsap or
setImmediate work well.
If you polyfill window.setImmediate or use Promise._immediateFn = yourImmediateFn it will be used instead of window.setTimeout
npm install setasap --save
import Promise from 'promise-polyfill/src/polyfill';
import setAsap from 'setasap';
Promise._immediateFn = setAsap;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
change this behavior by doing.
Promise._unhandledRejectionFn = <your reject error handler>;If you would like to disable unhandled rejection messages. Use a noop like below.
Promise._unhandledRejectionFn = function(rejectError) {};npm install
npm test
MIT