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.
IteratorconstructorIterator.prototypeIterator.concatIterator.fromIterator.zipIterator.zipKeyedIterator.prototype.constructorIterator.prototype.dropIterator.prototype.everyIterator.prototype.filterIterator.prototype.findIterator.prototype.flatMapIterator.prototype.forEachIterator.prototype.includesIterator.prototype.mapIterator.prototype.reduceIterator.prototype.someIterator.prototype.takeIterator.prototype.toArray
- node < v22, Chrome < v122, Safari <= v17.1, Firefox <= v125: not implemented
- node v22, Chrome v122 - v130: has a bug where
{ next: null }is not properly rejected - node v22 - v24, Chrome v122 - v134: missing early-error
IteratorClosewhen argument validation fails (e.g., non-callable mapper does not call the iterator'sreturnmethod) - all environments lack Iterator.concat, Iterator.zip, Iterator.zipKeyed, Iterator.prototype.includes
npm install --save es-iterator-helpersUsing 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” methodSimply clone the repo, npm install, and run npm test