The set() method of Map instances adds a new entry with a specified key and value to this Map, or updates an existing entry if the key already exists.

Try it

const map = new Map();
map.set("bar", "foo");

console.log(map.get("bar"));
// Expected output: "foo"

console.log(map.get("baz"));
// Expected output: undefined

Syntax

set(key, value)

Parameters

key

The key of the entry to add to or modify within the Map object. Can be any value. Object keys are compared by reference, not by value.

value

The value of the entry to add to or modify within the Map object. Can be any value.

Return value

The Map object.

Examples

Using set()

const myMap = new Map();

// Add new elements to the map
myMap.set("bar", "foo");
myMap.set(1, "foobar");

// Update an element in the map
myMap.set("bar", "baz");

Using the set() with chaining

Since the set() method returns back the same Map object, you can chain the method call like below:

// Add new elements to the map with chaining.
myMap.set("bar", "foo").set(1, "foobar").set(2, "baz");

Specifications

Browser compatibility

See also

• Map
• Map.prototype.delete()
• Map.prototype.get()
• Map.prototype.has()