Map.prototype.size

The size accessor property returns the number of elements in a Map object.

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

var myMap = new Map();
myMap.set('a', 'alpha');
myMap.set('b', 'beta');
myMap.set('g', 'gamma');

myMap.size // 3

Specifications

Specification
ECMAScript Language Specification (ECMAScript) # sec-get-map.prototype.size

Browser compatibility

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	WebView Android	Chrome Android	Firefox for Android	Opera Android	Safari on IOS	Samsung Internet
`size`	38	12	19 From Firefox 13 to Firefox 18, the `size` property was implemented as a `Map.prototype.size()` method, this has been changed to a property in later versions conform to the ECMAScript 2015 specification.	11	25	8	38	38	19 From Firefox 13 to Firefox 18, the `size` property was implemented as a `Map.prototype.size()` method, this has been changed to a property in later versions conform to the ECMAScript 2015 specification.	25	8	3.0