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4.1.0 • Public • Published


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Blessed polyfills for web platform features. Exports browser, Node, and Jest/jsdom polyfills where appropriate.

The following polyfills are currently provided:

  • base: ensures that all necessary JavaScript language features are polyfilled, including Map, Set, async functions, Symbol, and more.
  • fetch: Ensures a global WHATWG fetch function is available.
  • formdata: Ensures FormData is available globally (browser/ JSDom only).
  • idle-callback: Ensures requestIdleCallback and cancelIdleCallback are available globally (browser/ JSDom only).
  • intersection-observer: Ensures IntersectionObserver is available globally (browser/ JSDom only).
  • intl: Ensures Intl.PluralRules is defined.
  • mutation-observer: Ensures MutationObserver is available globally (browser/ JSDom only).


yarn add @shopify/polyfills


All you need to do is import the polyfills you use in your application:

import '@shopify/polyfills/base';
import '@shopify/polyfills/fetch';

In apps rendered on the client and server, we recommend importing these polyfills only once, in your top-level app component. Because this component is likely to be imported first by both the server and client bundles, the polyfills will be available throughout the application code. However, you may also need to import these files earlier in the execution of a Node server (if your server code uses features like fetch outside of the application). You will also likely need to import these in your test setup files, as most tests will not import the root app component.

Build configuration

This package also provides a way to configure your bundler to remap polyfill imports based on the environment being built. This allows you to import polyfills you need without worrying about whether they should be omitted in some cases, or omitted entirely. sewing-kit uses this feature automatically to ensure correct polyfills for tests, server builds, and client builds.

To make use of this feature, call mappedPolyfillsForEnv, exported from the root of this project, and pass in the environment being targeted. The environment must be one of node, jest, or a list of supported browsers (supplied as a browserslist-compatible query).

The following example shows how to use this feature to define Webpack aliases:

import {mappedPolyfillsForEnv} from '@shopify/polyfills';

// Server
module.exports = {
  resolve: {
    alias: mappedPolyfillsForEnv('node'),

// Client
module.exports = {
  resolve: {
    alias: mappedPolyfillsForEnv(['last 2 versions']),




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npm i @shopify/polyfills

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