1# array.prototype.flatmap <sup>[![Version Badge][npm-version-svg]][package-url]</sup> 2 3[![Build Status][travis-svg]][travis-url] 4[![dependency status][deps-svg]][deps-url] 5[![dev dependency status][dev-deps-svg]][dev-deps-url] 6[![License][license-image]][license-url] 7[![Downloads][downloads-image]][downloads-url] 8 9[![npm badge][npm-badge-png]][package-url] 10 11An ESnext spec-compliant `Array.prototype.flatMap` shim/polyfill/replacement that works as far down as ES3. 12 13This package implements the [es-shim API](https://github.com/es-shims/api) interface. It works in an ES3-supported environment and complies with the proposed [spec](https://tc39.github.io/proposal-flatMap/). 14 15Because `Array.prototype.flatMap` depends on a receiver (the `this` value), the main export takes the array to operate on as the first argument. 16 17## Getting started 18 19```sh 20npm install --save array.prototype.flatmap 21``` 22 23## Usage/Examples 24 25```js 26var flatMap = require('array.prototype.flatmap'); 27var assert = require('assert'); 28 29var arr = [1, [2], [], 3]; 30 31var results = flatMap(arr, function (x, i) { 32 assert.equal(x, arr[i]); 33 return x; 34}); 35 36assert.deepEqual(results, [1, 2, 3]); 37``` 38 39```js 40var flatMap = require('array.prototype.flatmap'); 41var assert = require('assert'); 42/* when Array#flatMap is not present */ 43delete Array.prototype.flatMap; 44var shimmedFlatMap = flatMap.shim(); 45 46var mapper = function (x) { return [x, 1]; }; 47 48assert.equal(shimmedFlatMap, flatMap.getPolyfill()); 49assert.deepEqual(arr.flatMap(mapper), flatMap(arr, mapper)); 50``` 51 52```js 53var flatMap = require('array.prototype.flatmap'); 54var assert = require('assert'); 55/* when Array#flatMap is present */ 56var shimmedIncludes = flatMap.shim(); 57 58var mapper = function (x) { return [x, 1]; }; 59 60assert.equal(shimmedIncludes, Array.prototype.flatMap); 61assert.deepEqual(arr.flatMap(mapper), flatMap(arr, mapper)); 62``` 63 64## Tests 65Simply clone the repo, `npm install`, and run `npm test` 66 67[package-url]: https://npmjs.org/package/array.prototype.flatmap 68[npm-version-svg]: http://versionbadg.es/es-shims/Array.prototype.flatMap.svg 69[travis-svg]: https://travis-ci.org/es-shims/Array.prototype.flatMap.svg 70[travis-url]: https://travis-ci.org/es-shims/Array.prototype.flatMap 71[deps-svg]: https://david-dm.org/es-shims/Array.prototype.flatMap.svg 72[deps-url]: https://david-dm.org/es-shims/Array.prototype.flatMap 73[dev-deps-svg]: https://david-dm.org/es-shims/Array.prototype.flatMap/dev-status.svg 74[dev-deps-url]: https://david-dm.org/es-shims/Array.prototype.flatMap#info=devDependencies 75[npm-badge-png]: https://nodei.co/npm/array.prototype.flatmap.png?downloads=true&stars=true 76[license-image]: http://img.shields.io/npm/l/array.prototype.flatmap.svg 77[license-url]: LICENSE 78[downloads-image]: http://img.shields.io/npm/dm/array.prototype.flatmap.svg 79[downloads-url]: http://npm-stat.com/charts.html?package=array.prototype.flatmap 80