How to make promises work in IE11

Question

I have a simple code that runs perfectly on every browser except for the Internet Explorer 11  How can I make it work on all browsers   Codepen  Thanks in advance    use strict    let promise   new Promise  resolve  reject    gt       setTimeout      gt        resolve  result         1000        promise    then      result   gt          alert  Fulfilled      result              error   gt          alert  Rejected      error

User · Accepted Answer

If you want this type of code to run in IE11 (which does not support much of ES6 at all), then you need to get a 3rd party promise library (like Bluebird), include that library and change your coding to use ES5 coding structures (no arrow functions, no let, etc...) so you can live within the limits of what older browsers support.

Or, you can use a transpiler (like Babel) to convert your ES6 code to ES5 code that will work in older browsers.

Here's a version of your code written in ES5 syntax with the Bluebird promise library:

<script src="https://cdnjs.cloudflare.com/ajax/libs/bluebird/3.3.4/bluebird.min.js"></script>

<script>

'use strict';

var promise = new Promise(function(resolve) {
    setTimeout(function() {
        resolve("result");
    }, 1000);
});

promise.then(function(result) {
    alert("Fulfilled: " + result);
}, function(error) {
    alert("Rejected: " + error);
});

</script>

User · Answer

You could try using a Polyfill  The following Polyfill was published in 2019 and did the trick for me  It assigns the Promise function to the window object   used like  window Promise https   www npmjs com package promise-polyfill  If you want more information on Polyfills check out the following MDN web doc https   developer mozilla org en-US docs Glossary Polyfill

[javascript] How to make promises work in IE11

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