@10xjs/polyfill-analyzer

> Analyze a javascript file to determine which polyfills are necessary to run it. Designed for use with polyfill-library.

Usage

Polyfill analyzer statically analyzes a string of javascript and returns an array of polyfill feature names compatible with with polyfill-library.

``js
import fs from 'fs';
import {analyze} from '@10xjs/polyfill-analyzer';

const features = analyze({
source: s.readFileSync('./bundle.js', 'utf-8'),
// include is a list of feature names to detect. Without a value provided,
// analyze will default to detecting all possible features (using
// polyfillLibrary.listAllPolyfills()). If you know your browser support
// target, include should be provided as the list of only the polyfills
// possibly needed for the targeted browsers.
include: [
'Symbol',
'Symbol.toStringTag',
'Symbol.iterator',
'Array.from',
'Object.entries',
'Array.prototype.findIndex',
'Object.keys',
'Object.getOwnPropertyDescriptor',
'Object.getOwnPropertyDescriptors',
],
// Configure the behavior when an an entry in the include array is not a
// detectable polyfill. (Not all features listed by
// polyfillLibrary.listAllPolyfills() can be detected.)
// Allowed values are "ignore", "warn", and "error";
unsupportedPolyfill: 'ignore',
});

// Returns an array of feature names which can be used to generate a custom
// polyfill bundle using polyfillLibrary.getPolyfillString().

// [
// 'Symbol',
// 'Symbol.toStringTag',
// 'Array.from',
// 'Object.keys',
// 'Object.getOwnPropertyDescriptor',
// 'Object.getOwnPropertyDescriptors',
// ]
``

API

$3

- @param {string} [options.source] Javascript source code.
- @param {string[]} [options.include] List of polyfills (from polyfill-library) to detect. Defaults to all detectable polyfills.
- @param {string[]} [options.exclude=[]] List of polyfills to ignore. The exclude list has precedence over the include list.
- @param {"ignore"|"warn"|"error"} [options.unsupportedPolyfill="error"] Specify the behavior when an included unsupported polyfill is encountered in the options.include` list.