lodash v4.0.0

2015 was big year! Lodash became the most depended on npm package, passed 1 billion downloads, & its v3 release saw massive adoption!

The year was also one of collaboration, as discussions began on merging Lodash & Underscore. Much of Lodash v4 is proofing out the ideas from those discussions. Lodash v4 would not be possible without the collaboration & contributions of the Underscore core team. In the spirit of merging our teams have blended with several members contributing to both libraries.

For 2016 & lodash v4.0.0 we wanted to cut loose, push forward, & take things up a notch!

Modern only

With v4 we’re breaking free from old projects, old environments, & dropping old IE < 9 support!

4 kB Core

Lodash’s kitchen-sink size will continue to grow as new methods & functionality are added. However, we now offer a 4 kB (gzipped) core build that’s compatible with Backbone v1.2.4 for folks who want Lodash without lugging around the kitchen sink.

More ES6

We’ve continued to embrace ES6 with methods like _.isSymbol, added support for cloning & comparing array buffers, maps, sets, & symbols, converting iterators to arrays, & iterable _(…).

In addition, we’ve published an es-build & pulled babel-plugin-lodash into core to make tree-shaking a breeze.

More Modular

Pop quiz! 📣

What category path does the bindAll method belong to? Is it

A) require('lodash/function/bindAll') B) require('lodash/utility/bindAll') C) require('lodash/util/bindAll')

Don’t know? Well, with v4 it doesn’t matter because now module paths are as simple as

var bindAll = require('lodash/bindAll');

We’ve also reduced module complexity making it easier to create smaller bundles. This has helped Lodash adoption with libraries like Async & Redux!

1st Class FP

With v3 we introduced lodash-fp. We learned a lot & with v4 we decided to pull it into core.

Now you can get immutable, auto-curried, iteratee-first, data-last methods as simply as

var _ = require('lodash/fp');
var object = { 'a': 1 };
var source = { 'b': 2 };
var newObject = _.assign(source)(object);

console.log(newObject);
// => { 'a': 1, 'b': 2 }

console.log(object);
// => { 'a': 1 }

var convert = require('lodash/fp/convert');
var assign = convert('assign', require('lodash.assign'));
// works too!

Chakra Optimized

Well actually, while we’re excited about Chakra, Lodash is optimized for great performance across all engines. Unlike many libraries, we don’t favor a single engine so we can deliver solid performance & support regardless of engine.

With v4 we’ve continued our commitment to performance; expanding support for lazy evaluation & improving the performance of core functionality like circular reference detection.

Emojis

Taking things up a notch Lodash v4 has added support for emojis! Includes things like astral symbols, unicode modifiers, variation selector characters, zero-width joiners, & regional indicator symbols.

<img src="https://cloud.githubusercontent.com/assets/4303/12280603/077c73ba-b944-11e5-900c-8463f8680612.png">

Breaking changes

We’ve introduced more breaking changes in this release than any other so be sure to check out the changelog for a full rundown of changes & give lodash-migrate a spin to help migrate older Lodash code to the latest release.

If you dig Lodash don’t forget to star the repo or npm star lodash!