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Does what native JavaScript doesn't.

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From my humble point of view, JavaScript is lacking of some very useful small built-in functions some other languages, like Python, have.

Yes, reduce and map can do quite a lot of things, in quite a lot of situations. They can also often save us in the most desparate situations. But because they are very generic tools, they do not provide a clear straight-forward understanding of what they are used/implemented for.

For example, let's say you want to count the occurences of a number in an array of numbers. For sure, you can do it with a reduce:

array.reduce((count, item) => item === itemToCount ? count + 1 : count, 0)

But let's be honest. Don't you think this is so verbose code for a simple count() ? Why is there not a built-in count function in JavaScript ?

This is exactly what js-extra is built for. Its aim is to provide explicit functions built on top of the native JavaScript functions. Since Lodash already provides many extra functions, the lib will aim to complete it with very specific functions.

With js-extra the above code becomes:

count(array, itemToCount)

How to use js-extra


$ yarn add js-extra


$ npm i js-extra

You can import the functions this way:


import { count } from 'js-extra'


var { count } = require('js-extra')

You can find all the implemented & available functions of the lib here.

js-extra is tree-shakeable and side-effects free!


The API is available here: js-extra API


Any contribution would be more than welcome! You think you can optimize the algorithms of existing functions ? Please, open a PR! :)

You would like to add a function that JavaScript doesn't have natively ? Please, go ahead and open a PR! :)

Found any bugs or you have some ideas ? Please, open an issue! :)

The following commands are executed with yarn, but you can of course use any package manager tool like npm or npx.

To install dependencies:

yarn install

To build the project:

yarn build

To run the tests:

yarn test

Before you commit:

yarn validate

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  • alelain