lodash.map

What is lodash.map?

The lodash.map package is a utility library that provides a method for creating a new array populated with the results of calling a provided function on every element in the calling array. It is part of the larger Lodash library, which offers a wide range of utility functions for common programming tasks.

What are lodash.map's main functionalities?

Basic Mapping

This feature allows you to apply a function to each element in an array and create a new array with the results. In this example, each number in the array is multiplied by 2.

const _ = require('lodash.map');
const array = [1, 2, 3, 4];
const result = _.map(array, function(n) { return n * 2; });
console.log(result); // [2, 4, 6, 8]

Mapping with Objects

This feature allows you to map over the values of an object and create a new array with the results. In this example, the ages of the users are extracted into a new array.

const _ = require('lodash.map');
const users = { 'fred': { 'user': 'fred', 'age': 40 }, 'pebbles': { 'user': 'pebbles', 'age': 1 } };
const result = _.map(users, function(user) { return user.age; });
console.log(result); // [40, 1]

Mapping with Index

This feature allows you to use the index of each element in the array during the mapping process. In this example, each number is multiplied by its index.

const _ = require('lodash.map');
const array = [1, 2, 3, 4];
const result = _.map(array, function(n, index) { return n * index; });
console.log(result); // [0, 2, 6, 12]

Other packages similar to lodash.map

underscore

Underscore is a JavaScript library that provides utility functions for common programming tasks. It includes a map function similar to lodash.map, but Lodash is generally considered to be faster and more modular.

ramda

Ramda is a functional programming library for JavaScript. It provides a map function that is similar to lodash.map but emphasizes immutability and function composition.

array-map

array-map is a lightweight package that provides a map function for arrays. It is less feature-rich compared to lodash.map but can be a good choice for simple use cases where a full utility library is not needed.

README

lodash.map v3.0.0

The modern build of lodash’s _.map exported as a Node.js/io.js module.

Installation

Using npm:

$ {sudo -H} npm i -g npm
$ npm i --save lodash.map

In Node.js/io.js:

var map = require('lodash.map');

See the documentation or package source for more details.