es-shimses-iterator-helpers 
An ESnext spec-compliant sync iterator helpers shim/polyfill/replacement that works as far down as ES3.
This package implements the es-shim API “multi” interface. It works in an ES3-supported environment and complies with the iterator helpers spec and the iterator sequencing spec.
Because the Iterator.prototype methods depend on a receiver (the this value), the main export in each subdirectory takes the iterator to operate on as the first argument.
The main export of the package itself is simply an array of the available directory names. It’s sole intended use is for build tooling and testing.
Supported things
IteratorconstructorIterator.prototypeIterator.concatIterator.fromIterator.zipIterator.zipKeyedIterator.prototype.constructorIterator.prototype.dropIterator.prototype.everyIterator.prototype.filterIterator.prototype.findIterator.prototype.flatMapIterator.prototype.forEachIterator.prototype.mapIterator.prototype.reduceIterator.prototype.someIterator.prototype.takeIterator.prototype.toArray
Environments where this is needed
- node v22, Chrome >= v122: has a bug
- node < v22, Chrome < v122, Safari <= v17.1, Firefox <= v125: not implemented
- all environments lack Iterator.concat, Iterator.zip, Iterator.zipKeyed
Getting started
npm install --save es-iterator-helpersUsage/Examples
Using explicit imports:
const map = require('es-iterator-helpers/Iterator.prototype.map');
const toArray = require('es-iterator-helpers/Iterator.prototype.toArray');
const assert = require('assert');
const iterator = [1, 2, 3].values();
const mapped = map(iterator, (x) => x + 10);
assert.deepEqual(
mapped.next(),
{
done: false,
value: 11,
}
);
assert.deepEqual(
toArray(mapped),
[12, 13]
);Shim using require:
require('es-iterator-helpers/auto'); // shim all of the methods
require('es-iterator-helpers/Iterator.prototype.map/auto'); // shim the “map” methodShim using import syntax:
import 'es-iterator-helpers/auto'; // shim all of the methods
import 'es-iterator-helpers/Iterator.prototype.map/auto'; // shim the “map” methodTests
Simply clone the repo, npm install, and run npm test