Underscore.JS - map method

Syntax

_.map(list, iteratee, [context]) 

map method produces a new array of values by mapping each value of list while iterating over a given list of element, call the iteratee function which is bound to context object, if passed. Iteratee is called with three parameters: (element, index, list). In case of JavaScript object, iteratee's object will be (value, key, list). Returns the list for chaining purpose.

Example

var _ = require('underscore');

//Example 1. get Square of each number of array
var list = _.map([1, 2, 3], function(x) { return x*x });
console.log(list);

//Example 2. get squre of each number of object
list = _.map({one: 1, two: 2, three: 3}, function(value, key) { return value*value });
console.log(list);

Save the above program in tester.js. Run the following command to execute this program.

Command

\>node tester.js

Output

[ 1, 4, 9 ]
[ 1, 4, 9 ]