Map.prototype.size
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.
The size
accessor property of Map
instances returns the number of elements in this map.
Try it
const map1 = new Map();
map1.set("a", "alpha");
map1.set("b", "beta");
map1.set("g", "gamma");
console.log(map1.size);
// Expected output: 3
Description
The value of size
is an integer representing how many entries the Map
object
has. A set accessor function for size
is undefined
; you can not change this
property.
Examples
Using size
js
const myMap = new Map();
myMap.set("a", "alpha");
myMap.set("b", "beta");
myMap.set("g", "gamma");
console.log(myMap.size); // 3
Specifications
Specification |
---|
ECMAScript® 2025 Language Specification # sec-get-map.prototype.size |
Browser compatibility
Report problems with this compatibility data on GitHubdesktop | mobile | server | ||||||||||||
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size |
Legend
Tip: you can click/tap on a cell for more information.
- Full support
- Full support
- See implementation notes.
The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.