Polyfill playground

This project uses Babel to replace missing functionality with core-js-pure "ponyfills" (polyfills as modules, without globally patching browser built-ins)

Browserslist config

See config .browserslistrc feature query for supports es6-module which targets only browsers supporting:

<script type="module" src="example.mjs"></script>

Polyfills required

The sample code in this project requires polyfills for the following supports es6-module browsers:

• 0.00 % - Chrome 61
• 0.00 % - Edge 16
• 0.00 % - Firefox 60
• 0.00 % - Opera 48
• 0.00 % - Safari 10.1 (macOS)
• 0.28 % - Safari 10.3 (iOS)
• 0.00 % - Samsung 8.2

Do we still need polyfills for browsers with 0.00% audience? See caniuse-db GB stats

Note: Adding the query and > 0.1% in GB to .browserslistrc would sensibly remove the large KB polyfill overhead as audience numbers drop below 0.1% over time

Output supported browsers from config:

npx browserslist

Modular standard library core-js

Typical polyfill imports for this project include:

Array iterator es.array.iterator

Supports array methods in:

• Chrome 61
• Opera 48
• Samsung 8.2

[].entries()
[].keys()
[].values()

DOM collections iterator web.dom-collections.iterator

Supports array methods on CSSRuleList, DOMTokenList, HTMLFormElement etc in:

• Chrome 61
• Edge 16
• Opera 48
• Safari 10.1 (macOS)
• Safari 10.3 (iOS)
• Samsung 8.2

Promise es.promise

To support:

• Chrome 61
• Edge 16
• Firefox 60
• Opera 48
• Safari 10.1 (macOS)
• Safari 10.3 (iOS)
• Samsung 8.2

Promise.all()
Promise.race()
Promise.reject()
Promise.resolve()

new Promise()
  .then()
  .catch()

String trim es.string.trim-end es.string.trim-start

To support:

• Chrome 61
• Edge 16
• Firefox 60
• Opera 48
• Safari 10.1 (macOS)
• Safari 10.3 (iOS)
• Samsung 8.2

''.trimEnd()
''.trimStart()