array.prototype.flatten

An ESnext spec-compliant Array.prototype.flatten shim/polyfill/replacement that works as far down as ES3.

This package implements the es-shim API interface. It works in an ES3-supported environment and complies with the proposed spec.

Because Array.prototype.flatten depends on a receiver (the this value), the main export takes the array to operate on as the first argument.

Getting started

npm install --save array.prototype.flatten

Usage/Examples

var flatten = require('array.prototype.flatten');
var assert = require('assert');

var arr = [1, [2], [], 3, [[4]]];

assert.deepEqual(flatten(arr, 1), [1, 2, 3, [4]]);

var flatten = require('array.prototype.flatten');
var assert = require('assert');
/* when Array#flatten is not present */
delete Array.prototype.flatten;
var shimmedFlatten = flatten.shim();

assert.equal(shimmedFlatten, flatten.getPolyfill());
assert.deepEqual(arr.flatten(), flatten(arr));

var flatten = require('array.prototype.flatten');
var assert = require('assert');
/* when Array#flatten is present */
var shimmedIncludes = flatten.shim();

var mapper = function (x) { return [x, 1]; };

assert.equal(shimmedIncludes, Array.prototype.flatten);
assert.deepEqual(arr.flatten(mapper), flatten(arr, mapper));

Tests

Simply clone the repo, npm install, and run npm test