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 map = new Map();
map.set("a", "alpha");
map.set("b", "beta");
map.set("g", "gamma");
console.log(map.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® 2026 Language Specification # sec-get-map.prototype.size |
Browser compatibility
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