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# collection-map [![NPM version](https://img.shields.io/npm/v/collection-map.svg?style=flat)](https://www.npmjs.com/package/collection-map) [![NPM monthly downloads](https://img.shields.io/npm/dm/collection-map.svg?style=flat)](https://npmjs.org/package/collection-map) [![NPM total downloads](https://img.shields.io/npm/dt/collection-map.svg?style=flat)](https://npmjs.org/package/collection-map) [![Linux Build Status](https://img.shields.io/travis/jonschlinkert/collection-map.svg?style=flat&label=Travis)](https://travis-ci.org/jonschlinkert/collection-map)
> Returns an array of mapped values from an array or object.
## Install
Install with [npm](https://www.npmjs.com/):
```sh
$ npm install --save collection-map
```
Inspired by the [collections/map](http://moutjs.com/) util in mout.
## Usage
```js
var map = require('collection-map');
```
### objects
```js
var res = map({a: 'foo', b: 'bar', c: 'baz'}, function(item, key, obj) {
return item;
});
console.log(res);
// => ['foo', 'bar', 'baz']
var res = map({a: 'foo', b: 'bar', c: 'baz'}, function(item, key, obj) {
return key;
});
console.log(res);
// => ['a', 'b', 'c']
```
### arrays
```js
var res = map(['foo', 'bar', 'baz'], function(item, index, array) {
return item;
});
console.log(res);
// => ['foo', 'bar', 'baz']
var res = map(['foo', 'bar', 'baz'], function(item, index, array) {
return index;
});
console.log(res);
// => [0, 1, 2]
```
### strings
A string may be passed as the second argument, for getting properties:
```js
var obj = {
a: {aaa: 'one', bbb: 'four', ccc: 'seven'},
b: {aaa: 'two', bbb: 'five', ccc: 'eight'},
c: {aaa: 'three', bbb: 'six', ccc: 'nine'}
};
console.log(map(obj, 'aaa'));
// => ['one', 'two', 'three']
var array = [obj.a, obj.b, obj.c];
console.log(map(array, 'bbb'));
// => ['four', 'five', 'six']
```
### thisArg
Invocation context may be passed as the last argument.
```js
var array = ['a', 'b', 'c'];
var ctx = {a: 'aaa', b: 'bbb', c: 'ccc'};
var res = map(array, function(item, index, array) {
return this[item];
}, ctx);
console.log(res);
// => ['aaa', 'bbb', 'ccc']
```
## About
### Related projects
* [arr-flatten](https://www.npmjs.com/package/arr-flatten): Recursively flatten an array or arrays. This is the fastest implementation of array flatten. | [homepage](https://github.com/jonschlinkert/arr-flatten "Recursively flatten an array or arrays. This is the fastest implementation of array flatten.")
* [arr-map](https://www.npmjs.com/package/arr-map): Faster, node.js focused alternative to JavaScript's native array map. | [homepage](https://github.com/jonschlinkert/arr-map "Faster, node.js focused alternative to JavaScript's native array map.")
* [for-in](https://www.npmjs.com/package/for-in): Iterate over the own and inherited enumerable properties of an object, and return an object… [more](https://github.com/jonschlinkert/for-in) | [homepage](https://github.com/jonschlinkert/for-in "Iterate over the own and inherited enumerable properties of an object, and return an object with properties that evaluate to true from the callback. Exit early by returning `false`. JavaScript/Node.js")
* [for-own](https://www.npmjs.com/package/for-own): Iterate over the own enumerable properties of an object, and return an object with properties… [more](https://github.com/jonschlinkert/for-own) | [homepage](https://github.com/jonschlinkert/for-own "Iterate over the own enumerable properties of an object, and return an object with properties that evaluate to true from the callback. Exit early by returning `false`. JavaScript/Node.js.")
### Contributing
Pull requests and stars are always welcome. For bugs and feature requests, [please create an issue](../../issues/new).
### Building docs
_(This project's readme.md is generated by [verb](https://github.com/verbose/verb-generate-readme), please don't edit the readme directly. Any changes to the readme must be made in the [.verb.md](.verb.md) readme template.)_
To generate the readme, run the following command:
```sh
$ npm install -g verbose/verb#dev verb-generate-readme && verb
```
### Running tests
Running and reviewing unit tests is a great way to get familiarized with a library and its API. You can install dependencies and run tests with the following command:
```sh
$ npm install && npm test
```
### Author
**Jon Schlinkert**
* [github/jonschlinkert](https://github.com/jonschlinkert)
* [twitter/jonschlinkert](https://twitter.com/jonschlinkert)
### License
Copyright © 2017, [Jon Schlinkert](https://github.com/jonschlinkert).
Released under the [MIT License](LICENSE).
***
_This file was generated by [verb-generate-readme](https://github.com/verbose/verb-generate-readme), v0.4.3, on March 02, 2017._