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.
Thesize accessor property ofMap instances returns the number of elements in this map.
Try it
const map = new Map();map.set("a", "alpha");map.set("b", "beta");map.set("g", "gamma");console.log(map.size);// Expected output: 3Description
The value ofsize is an integer representing how many entries theMap objecthas. A set accessor function forsize isundefined; you can not change thisproperty.
Examples
Using size
js
const myMap = new Map();myMap.set("a", "alpha");myMap.set("b", "beta");myMap.set("g", "gamma");console.log(myMap.size); // 3Specifications
| Specification |
|---|
| ECMAScript® 2026 Language Specification # sec-get-map.prototype.size |