Polyfill.io is a service that serves JavaScript polyfills.

## 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>if(!(window.Promise&&[].includes&&Object.assign&&window.Map)){document.write('<script src="https://cdn.polyfill.io/v2/polyfill.min.js"></scr'+'ipt>')}</script>

This only includes polyfill.io when necessary, skipping it for modern browsers for faster load times.

### Extra features

    <script>if(!(window.fetch&&window.Promise&&[].includes&&Object.assign&&window.Map)){document.write('<script src="https://cdn.polyfill.io/v2/polyfill.min.js?features=default,fetch"></scr'+'ipt>')}</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.

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