Map.prototype.set()
BaselineWidely 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 or updates an entry in this map with a specified key and a value.
Try it
const map1 = new Map();map1.set("bar", "foo");console.log(map1.get("bar"));// Expected output: "foo"console.log(map1.get("baz"));// Expected output: undefinedSyntax
js
set(key, value)Parameters
keyThe key of the element to add to the
Mapobject. The key may be anyJavaScript type (anyprimitive value or any type ofJavaScript object).valueThe value of the element to add to the
Mapobject. The value may be anyJavaScript type (anyprimitive value or any type ofJavaScript object).
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 themethod 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 |