Usage
Default usage
<script src="https://cdn.polyfill.io/v2/polyfill.min.js"></script>
This is the default script for Polyfill.io.
References
- API example (polyfill.io)
- List of features (polyfill.io)
Optimized
For modern browsers
<script>(function(d,s){
if(window.Promise&&[].includes&&Object.assign&&window.Map)return;
var sc=d.getElementsByTagName(s)[0],js=d.createElement(s);
js.src='https://cdn.polyfill.io/v2/polyfill.min.js';
sc.parentNode.insertBefore(js, sc);
}(document,'script'))</script>
This only includes polyfill.io when necessary, skipping it for modern browsers for faster load times.
Extra features
<script>(function(d,s){
if(window.fetch&&window.Promise&&[].includes&&Object.assign&&window.Map)return;
var sc=d.getElementsByTagName(s)[0],js=d.createElement(s);
js.src='https://cdn.polyfill.io/v2/polyfill.min.js?features=default,fetch';
sc.parentNode.insertBefore(js, sc);
}(document,'script'))</script>
This is the same as the previous, but also adds a polyfill for window.fetch(). We add a window.fetch check and loads the additional fetch feature.