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 | Status | Comment |
---|---|---|
ECMAScript 2015 (6th Edition, ECMA-262) The definition of 'Map.prototype.size' in that specification. |
Standard | Initial definition. |
ECMAScript 2017 Draft (ECMA-262) The definition of 'Map.prototype.size' in that specification. |
Draft |
Browser compatibility
Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari |
---|---|---|---|---|---|
Basic support | 38 | 19 (19) | 11 | 25 | 7.1 |
Feature | Android | Chrome for Android | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile |
---|---|---|---|---|---|---|
Basic support | No support | 38 | 19.0 (19) | No support | No support | 8 |
Gecko-specific notes
- From Gecko 13 (Firefox 13 / Thunderbird 13 / SeaMonkey 2.10) to Gecko 18 (Firefox 18 / Thunderbird 18 / SeaMonkey 2.15 / Firefox OS 1.0.1 / Firefox OS 1.1) 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 6 specification (bug 807001).
See also
Document Tags and Contributors
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Contributors to this page:
fscholz,
realityking
Last updated by:
fscholz,