Promyfill

Promyfill saves you from shipping polyfill code to all browsers.
Your own polyfill URL will be loaded only if needed.

✅ Promyfill is ~450 Bytes.

Usage

Fetch example

const fetchPolyfill = 'https://rawgit.com/github/fetch/master/fetch.js';

promyfill(window.fetch, fetchPolyfill).then((fetch) => {
    //fetch is available (polyfill is fetched only if needed)
    fetch('users.json');
});

Alternate usage

const fetchPolyfill = 'https://rawgit.com/github/fetch/master/fetch.js';

promyfill('fetch' in window, fetchPolyfill).then(() => {
    //fetch is available (polyfill is fetched only if needed)
    fetch('users.json');
});

Intersection observer example

const ioPolyfill = 'https://rawgit.com/WICG/IntersectionObserver/gh-pages/polyfill/intersection-observer.js';

promyfill('IntersectionObserver' in window, ioPolyfill).then(() => {
    const io = new IntersectionObserver(() => {});
})

"Promises" support

Promyfill relies on native promises available in most modern browsers, except a few such as IE11, Android 4.4].
In order to support these browsers, you can also include the tiny promis from bramstein

Video explanation

Feedback

This is a PWA experiment, usage & motivation detailed in this Medium article
For feedback or questions, please open a new issue.