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JavaScript Map set() Method - GeeksforGeeks

Last Updated : 23 Jul, 2025

The JavaScript map.set() method is used to add key-value pairs to a Map object. It can also be used to update the value of an existing key. Each value must have a unique key so that they get mapped correctly.

GFGmap.set(key, value);

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

• Key: This is the key of the item that has to be added or updated in the Map.
• Value: This is the value of the item that has to be added or updated in the Map.

Example 1:

let GFGMap = new Map();

// Adding a key value pair
GFGMap.set(1, "India");

// Getting the value by key
console.log(GFGMap.get(1));

// Updating the existing value
GFGMap.set(1, "England");

// Getting the value back
console.log(GFGMap.get(1));

Output:

India
England

Example 2: Using set() with chaining

let myMap = new Map();

// Adding key value pair with chaining
myMap.set(1, "Rohan").set(2, "Sohan").set(3, "Trojan");

// Getting the values back
console.log(myMap.get(1));
console.log(myMap.get(2));
console.log(myMap.get(3));

Output:

Rohan
Sohan
Trojan

• Chrome 38
• Edge 12
• Firefox 13
• Opera 25
• Safari 8

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