The Map() constructor is used to create Map objects in JavaScript. The map is a data structure that stores elements as a key, value pair.
Syntax:
new Map() new Map(iterable)
Parameters:
- iterable: An iterable object used for iterating through elements, stored as a key, value pair.
Return value: A new Map object returns after the initialization of the map constructor.
Example 1:
Javascript
// map1 contains // 1 => 10 // 2 => 20 // 3 => 30 // 4 => 40 let map1 = new Map([
[1, 10], [2, 20],
[3, 30], [4, 40]
]); console.log( "Map1: " );
console.log(map1); |
Output:
Map1: Map(4) { 1 => 10, 2 => 20, 3 => 30, 4 => 40 }
Example 2:
Javascript
// map2 contains // firstname => Ram // lastname => Prasad // website => geeksforgeeks let map2 = new Map([
[ "firstname" , "Ram" ],
[ "lastname" , "Prasad" ],
[ "website" , "geeksforgeeks" ]
]); console.log( "Map2: " );
console.log(map2); |
Output:
Map2: Map(3) { 'firstname' => 'Ram', 'lastname' => 'Prasad', 'website' => 'geeksforgeeks' }
Example 3:
Javascript
// Map contains nested array let map3 = new Map([
[ "whole numbers" , [1, 2, 3, 4]],
[ "Decimal numbers" , [1.1, 1.2, 1.3, 1.4]],
[ "negative numbers" , [-1, -2, -3, -4]]
]); console.log( "Map3: " );
console.log(map3); |
Output:
Map3: Map(3) { 'whole numbers' => [ 1, 2, 3, 4], 'Decimal numbers' => [ 1.1, 1.2, 1.3, 1.4], 'negative numbers' => [ -1, -2, -3, -4] }
Supported Browsers:
- Chrome 38 and above
- Edge 12 and above
- Firefox 13 and above
- Internet Explorer 11 and above
- Opera 25 and above
- Safari 8 and above
We have a complete list of Javascript Map methods, to check those please go through this JavaScript MapComplete Reference article.