`Map.prototype.size`

The number of key/value pairs in a Map.

Since ES2015 (ES6) Spec ↗

Syntax

map.size

number — The count of entries currently in the map.

const m = new Map([["a", 1], ["b", 2]]);
console.log(m.size);

Output

const m = new Map();
m.set("x", 1);
m.delete("x");
console.log(m.size);

Output

- A read-only accessor property, unlike array `length` which is assignable. - `Set` has an equivalent `size` property.