Map.prototype.set()
Baseline Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.
Theset() method ofMap instances adds a new entry with a specified key and value to thisMap, 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: undefinedSyntax
js
set(key, value)Parameters
Return value
TheMap object.
Examples
Using set()
js
const myMap = new Map();// Add new elements to the mapmyMap.set("bar", "foo");myMap.set(1, "foobar");// Update an element in the mapmyMap.set("bar", "baz");Using the set() with chaining
Since theset() method returns back the sameMap object, you can chain the method call like below:
js
// Add new elements to the map with chaining.myMap.set("bar", "foo").set(1, "foobar").set(2, "baz");Specifications
| Specification |
|---|
| ECMAScript® 2026 Language Specification # sec-map.prototype.set |