polyfills-db

3.0.0 verified Sat Apr 25 auth: no javascript

A database of browser polyfill features, version 3.0.0, released as needed. Provides structured metadata about which browsers support each feature and which modules/files implement it. Supports runtime JS polyfills, recast-based JS transpilation, and postcss-based CSS transpilation. Key differentiator: centralized polyfill data for multiple transpilation targets, manually maintained with community contributions. Release cadence: irregular, stable.

Common errors

error Error [ERR_REQUIRE_ESM]: require() of ES Module /path/to/polyfills-db not supported. ↓

cause Using require() with v3 ESM package.

fix

Switch to import: import polyfillsDB from 'polyfills-db'

error TypeError: Cannot read property 'browsers' of undefined ↓

cause Accessing data[feature] where feature key does not exist in the database.

fix

Check the feature exists in the features array before accessing data[feature].browsers.

error SyntaxError: Unexpected token 'export' ↓

cause Node.js version <12 without ESM support, or missing 'type':'module' in package.json.

fix

Update Node.js to >=12 and add 'type':'module' to your package.json.

Warnings

breaking polyfills-db v3 is ESM-only; require() throws ERR_REQUIRE_ESM. ↓

fix Use import syntax or dynamic import().

deprecated The data format changed in v3: previously flat arrays now nested objects. ↓

fix Update to access data[feature].browsers and data[feature].polyfills.

gotcha The 'regenerator' feature includes 'es7-async-fn'; do not use both or runtime duplication occurs. ↓

fix When using regenerator, omit es7-async-fn from polyfill list.

gotcha Manually maintained; browser support data may be outdated for recent browser versions. ↓

fix Cross-check with caniuse.com or MDN for latest data.

deprecated Version 2.x used CJS; v3 drops CJS support entirely. ↓

fix Node.js v12+ supports ESM; add 'type':'module' to package.json.

Install

npm install polyfills-db

yarn add polyfills-db

pnpm add polyfills-db

Imports

polyfills-db
wrong
```
const polyfillsDB = require('polyfills-db')
```
correct
```
import polyfillsDB from 'polyfills-db'
```
Default import is supported. ESM-only since v3. CJS require() will not work.

data

wrong

const { data } = require('polyfills-db')

correct

import { data } from 'polyfills-db'

Named export for the raw database object. ESM-only.

features

wrong

import features from 'polyfills-db'

correct

import { features } from 'polyfills-db'

Named export, not default. List of feature keys.

browsers
```
import { browsers } from 'polyfills-db'
```
Named export for browser support matrix.

Quickstart

Shows basic usage: import database, list features, and check browser support.

import polyfillsDB, { data, features, browsers } from 'polyfills-db';
// Log all feature keys
console.log(features);
// Check browser support for a feature
const feature = 'es6-array-from';
if (data[feature]) {
  console.log(`Browsers supporting ${feature}:`, data[feature].browsers);
}
// List available browsers
console.log('Browsers:', browsers);
// The database is a plain object; iterate features
for (const feat of features) {
  console.log(feat, data[feat].polyfills);
}