Lodash _.map() Method

Lodash is a JavaScript library that works on the top of underscore.js. Lodash helps in working with arrays, collection, strings, objects, numbers etc.

The _.map() method creates an array of values by running each element in collection through the iteratee. There are many lodash methods that are guarded to work as iteratees for methods like _.every(), _.filter(), _.map(), _.mapValues(), _.reject(), and _.some() methods.

Syntax:

_.map( collection, iteratee )

Parameters: This method accepts two parameters as mentioned above and described below:

• collection: This parameter holds the collection to iterate over.
• iteratee: This parameter holds the function invoked per iteration.

Return Value: This method returns the new mapped array.

Example 1:

// Requiring the lodash library
const _ = require("lodash");

// Original array
var array = _.map([5, 18]);

// Use of _.map() method
let mapped_array = _.map(array, function square(n) {
  return n * n;
})

// Printing the output
console.log(mapped_array);

Output:

[ 25, 324 ]

Example 2:

// Requiring the lodash library
const _ = require("lodash");

// Original array
var array = _.map({ 'x': 14, 'y': 28 });

// Use of _.map() method
let mapped_array = _.map(array, function square(n) {
  return n * n;
})

// Printing the output
console.log(mapped_array);

Output:

[ 196, 784 ]

Example 3:

// Requiring the lodash library
const _ = require("lodash");

// Original array
var users = [
  { 'user': 'jonny' },
  { 'user': 'john' }
];

// Use of _.map() method
// The `_.property` iteratee shorthand
let mapped_array = _.map(users, 'user');

// Printing the output
console.log(mapped_array);

Output:

[ 'jonny', 'john' ]