JavaScript Map set() Method

Last Updated : 08 Mar, 2021

The 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.

Syntax:

GFGmap.set(key, value);

Parameters: 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.

The examples below illustrate the set() method:

Example 1:

Javascript

<script> 
  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)); 
</script> 

Output :

India
England

Example 2: Using set() with chaining

Javascript

<script> 
  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)); 
</script> 