133 lines
4.6 KiB
Markdown
133 lines
4.6 KiB
Markdown
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# collection-map [](https://www.npmjs.com/package/collection-map) [](https://npmjs.org/package/collection-map) [](https://npmjs.org/package/collection-map) [](https://travis-ci.org/jonschlinkert/collection-map)
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> Returns an array of mapped values from an array or object.
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## Install
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Install with [npm](https://www.npmjs.com/):
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```sh
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$ npm install --save collection-map
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```
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Inspired by the [collections/map](http://moutjs.com/) util in mout.
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## Usage
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```js
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var map = require('collection-map');
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```
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### objects
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```js
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var res = map({a: 'foo', b: 'bar', c: 'baz'}, function(item, key, obj) {
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return item;
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});
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console.log(res);
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// => ['foo', 'bar', 'baz']
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var res = map({a: 'foo', b: 'bar', c: 'baz'}, function(item, key, obj) {
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return key;
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});
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console.log(res);
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// => ['a', 'b', 'c']
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```
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### arrays
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```js
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var res = map(['foo', 'bar', 'baz'], function(item, index, array) {
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return item;
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});
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console.log(res);
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// => ['foo', 'bar', 'baz']
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var res = map(['foo', 'bar', 'baz'], function(item, index, array) {
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return index;
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});
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console.log(res);
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// => [0, 1, 2]
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```
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### strings
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A string may be passed as the second argument, for getting properties:
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```js
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var obj = {
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a: {aaa: 'one', bbb: 'four', ccc: 'seven'},
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b: {aaa: 'two', bbb: 'five', ccc: 'eight'},
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c: {aaa: 'three', bbb: 'six', ccc: 'nine'}
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};
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console.log(map(obj, 'aaa'));
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// => ['one', 'two', 'three']
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var array = [obj.a, obj.b, obj.c];
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console.log(map(array, 'bbb'));
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// => ['four', 'five', 'six']
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```
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### thisArg
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Invocation context may be passed as the last argument.
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```js
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var array = ['a', 'b', 'c'];
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var ctx = {a: 'aaa', b: 'bbb', c: 'ccc'};
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var res = map(array, function(item, index, array) {
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return this[item];
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}, ctx);
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console.log(res);
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// => ['aaa', 'bbb', 'ccc']
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```
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## About
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### Related projects
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* [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.")
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* [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.")
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* [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")
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* [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.")
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### Contributing
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Pull requests and stars are always welcome. For bugs and feature requests, [please create an issue](../../issues/new).
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### Building docs
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_(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.)_
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To generate the readme, run the following command:
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```sh
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$ npm install -g verbose/verb#dev verb-generate-readme && verb
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```
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### Running tests
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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:
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```sh
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$ npm install && npm test
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```
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### Author
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**Jon Schlinkert**
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* [github/jonschlinkert](https://github.com/jonschlinkert)
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* [twitter/jonschlinkert](https://twitter.com/jonschlinkert)
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### License
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Copyright © 2017, [Jon Schlinkert](https://github.com/jonschlinkert).
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Released under the [MIT License](LICENSE).
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***
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_This file was generated by [verb-generate-readme](https://github.com/verbose/verb-generate-readme), v0.4.3, on March 02, 2017._
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