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An ESnext spec-compliant Array.prototype.groupToMap 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.groupToMap depends on a receiver (the this value), the main export takes the array to operate on as the first argument.

Getting started

``sh
npm install --save array.prototype.grouptomap
`

Usage/Examples

`js
var groupToMap = require('array.prototype.grouptomap');
var assert = require('assert');

var arr = [0, 1, 2, 3, 4, 5];
var parity = function (x) { return x % 2 === 0 ? 'even' : 'odd'; };

var results = groupToMap(arr, function (x, i, a) {
assert.equal(x, arr[i]);
assert.equal(a, arr);
return parity(x);
});

assert.deepEqual(results, new Map([
['even', [0, 2, 4]],
['odd', [1, 3, 5]],
]));
`

`js
var groupToMap = require('array.prototype.grouptomap');
var assert = require('assert');
/ when Array#groupToMap is not present /
delete Array.prototype.groupToMap;
var shimmed = groupToMap.shim();

assert.equal(shimmed, groupToMap.getPolyfill());
assert.deepEqual(arr.groupToMap(parity), groupToMap(arr, parity));
`

`js
var groupToMap = require('array.prototype.grouptomap');
var assert = require('assert');
/ when Array#groupToMap is present /
var shimmed = groupToMap.shim();

assert.equal(shimmed, Array.prototype.groupToMap);
assert.deepEqual(arr.groupToMap(parity), groupToMap(arr, parity));
`

Tests


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

[package-url]: https://npmjs.org/package/array.prototype.grouptomap
[npm-version-svg]: https://versionbadg.es/es-shims/Array.prototype.groupToMap.svg
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[dev-deps-url]: https://david-dm.org/es-shims/Array.prototype.groupToMap#info=devDependencies
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[license-url]: LICENSE
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