underscore

What is underscore?

The underscore npm package is a utility-belt library for JavaScript that provides a lot of the functional programming support that you would expect in Prototype.js (or Ruby), but without extending any of the built-in JavaScript objects. It includes a wide range of functions for collections, arrays, functions, objects, and more.

What are underscore's main functionalities?

Collections

Iterates over a list of elements, yielding each in turn to an iteratee function.

_.each([1, 2, 3], function(num) { console.log(num); });

Arrays

Produces a duplicate-free version of the array.

_.uniq([1, 2, 1, 4, 1, 3]);

Functions

Curries a function so that it can be called with fewer arguments than it expects.

var greet = function(name) { return 'hi: ' + name; }; var greetCurried = _.curry(greet); greetCurried('Bob');

Objects

Copy all of the properties in the source objects over to the destination object.

_.extend({name: 'moe'}, {age: 50});

Utilities

Returns a random integer between the given min and max, inclusive.

_.random(0, 100);

Other packages similar to underscore

lodash

Lodash is a modern JavaScript utility library delivering modularity, performance, & extras. It is often considered as a drop-in replacement for Underscore with additional features and improved performance.

ramda

Ramda is a practical functional library for JavaScript programmers. It emphasizes a purer functional style, immutability, and function composition, making it quite different from Underscore in terms of API design and usage patterns.

lazy.js

Lazy.js is a functional utility library similar to Underscore and Lodash, but with a focus on lazy evaluation, which can lead to significant performance improvements for certain types of operations on large datasets.

README

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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.

For Docs, License, Tests, and pre-packed downloads, see: http://documentcloud.github.com/underscore/

Many thanks to our contributors: https://github.com/documentcloud/underscore/contributors