JavaScript Map set()
Syntax & Examples

Map.set() method

The set() method of the Map object in JavaScript sets the value for the passed key in the Map object and returns the Map object.

Syntax of Map.set()

The syntax of Map.set() method is:

set(key, value)

This set() method of Map sets the value for the passed key in the Map object. Returns the Map object.

Parameters

ParameterOptional/RequiredDescription
keyrequiredThe key of the element to add to the Map.
valuerequiredThe value of the element to add to the Map.

Return Type

Map.set() returns value of type Map.


✐ Examples

1 Using set() to add a key-value pair to a Map

In JavaScript, we can use the set() method to add a key-value pair to a Map object.

For example,

  1. Create a new Map object map.
  2. Use the set() method to add the key 'a' with the value 1 to the map.
  3. Log the map to the console using console.log().

JavaScript Program

const map = new Map();
map.set('a', 1);
console.log(map);

Output

Map { 'a' => 1 }

2 Using set() to update a value in a Map

In JavaScript, we can use the set() method to update the value of an existing key in a Map object.

For example,

  1. Create a new Map object map with an initial key-value pair 'a' => 1.
  2. Use the set() method to update the value of the key 'a' to 2 in the map.
  3. Log the map to the console using console.log().

JavaScript Program

const map = new Map([['a', 1]]);
map.set('a', 2);
console.log(map);

Output

Map { 'a' => 2 }

3 Using set() with different types of keys

In JavaScript, we can use the set() method to add key-value pairs to a Map object where keys can be of different types.

For example,

  1. Create a new Map object map.
  2. Use the set() method to add a key-value pair with a string key 'a' and a value 1 to the map.
  3. Use the set() method to add a key-value pair with a number key 2 and a value 'b' to the map.
  4. Use the set() method to add a key-value pair with an object key { key: 'c' } and a value 3 to the map.
  5. Log the map to the console using console.log().

JavaScript Program

const map = new Map();
map.set('a', 1);
map.set(2, 'b');
map.set({ key: 'c' }, 3);
console.log(map);

Output

Map { 'a' => 1, 2 => 'b', { key: 'c' } => 3 }

Summary

In this JavaScript tutorial, we learned about set() method of Map: the syntax and few working examples with output and detailed explanation for each example.