__
                  /\ \                                                         __
 __  __    ___    \_\ \     __   _ __   ____    ___    ___   _ __    __       /\_\    ____
/\ \/\ \ /' _ `\  /'_  \  /'__`\/\  __\/ ,__\  / ___\ / __`\/\  __\/'__`\     \/\ \  /',__\
\ \ \_\ \/\ \/\ \/\ \ \ \/\  __/\ \ \//\__, `\/\ \__//\ \ \ \ \ \//\  __/  __  \ \ \/\__, `\
 \ \____/\ \_\ \_\ \___,_\ \____\\ \_\\/\____/\ \____\ \____/\ \_\\ \____\/\_\ _\ \ \/\____/
  \/___/  \/_/\/_/\/__,_ /\/____/ \/_/ \/___/  \/____/\/___/  \/_/ \/____/\/_//\ \_\ \/___/
                                                                              \ \____/
                                                                               \/___/

Underscore.js is a utility-belt library for JavaScript that provides support for the usual functional suspects (each, map, reduce, filter...) without extending any core JavaScript objects. It's available in ES6 and UMD (cjs, amd, iife) formats

ES6 & Beyond usage:

• partial importation of features (just import what you need, with a name that suits you).

import _template from 'underscore-es/template';

var basicTemplate = _template("Ok, i use <%= builder %> for my es6 and beyond stuff !");
var result = basicTemplate({builder: 'rollup'});
console.log( result ); 
// => "Ok, i use rollup for my es6 and beyond stuff !"

nb: only _chain isn't available in this case. another way to use chaining feature here is through _compose or _use.

import _use from 'underscore-es/use';
import _initial from 'underscore-es/initial';
import _filter from 'underscore-es/filter';
import _union from 'underscore-es/union';
import _last from 'underscore-es/last';

function note (num) {return 'result: '+ (num + 10) + " / 20"}
var test = _use([1, 2, 3, 6, 9])
          .do(_union, [1, 3, 11], [2, 6])
          .do([], Array.prototype.concat, [10, 14]) // or simply .do([], [].concat, [10, 14])
          .do(_filter, (num) => num % 2 == 0)
          .do(_initial)
          .do(_last)
          .do(note)
          .value();
console.log( test );
// => result: 20 / 20

import features depending of their category

import * as $co from 'underscore-es/_collections';
import * as $ar from 'underscore-es/_arrays';
import * as $ob from 'underscore-es/_objects';
import * as $fu from 'underscore-es/_functions';
import * as $ut from 'underscore-es/_utilities';

console.log( $ar._union([4,7], [7,0,3]) );
// => [4, 7, 0, 3]

• global importation of all features

import _ from 'underscore-es'; // or from 'underscore-es/_namespace'

_.chain([4,7])
 .union([7,0,3])
 .initial()
 .reverse()
 .head()
 .value()
 // => 0

• breaking changes

Since this underscore source code has been rewritten to be more es6 friendly :

the _.templateSettings property is now _.template.settings

import _template from 'underscore-es/template';

_template.settings = {
   evaluate: /\{\{([\s\S]+?)\}\}/g,
   interpolate: /\{\{=([\s\S]+?)\}\}/g
};

var custom = _template('<ul>{{ for (var key in people) { }}<li>{{= people[key] }}</li>{{ } }}</ul>');
var result = custom({people: {moe: 'Moe', larry: 'Larry', curly: 'Curly'}});
console.log( result );
// => <ul><li>Moe</li><li>Larry</li><li>Curly</li></ul>

the _.iteratee shall now (for global importation) be overwritten through _.setIteratee([fn]) method

import _iteratee, {_setIteratee} from './underscore-es/iteratee';
import _countBy from './underscore-es/countBy';
import _isRegExp from './underscore-es/isRegExp';
import _filter from './underscore-es/filter';

_setIteratee( function(value) {
   // RegEx values return a function that returns the number of matches
   if (_isRegExp(value)) return function(obj) {
      return (obj.match(value) || []).length;
   };
   return value;
});

// test some methods that claim to be transformed through `_iteratee`
var collection = ['foo', 'bar', 'bbiz'];
console.log(_countBy(collection, /b/g))
// => {0: 1, 1: 1, 2: 1}
console.log(_filter(collection, /b/g))
// => ['bar', 'bbiz']

Documentation is the place to find what you need to know !

This project adheres to a code of conduct. By participating, you are expected to uphold this code.

For support and questions, please use the gitter channel or stackoverflow

Underscore is an open-sourced component of DocumentCloud: https://github.com/documentcloud

Many thanks to our contributors: https://github.com/tnga/underscore-es/contributors https://github.com/jashkenas/underscore/contributors