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


The value of size is an integer representing how many entries the Set object has. A set accessor function for size is undefined; you cannot change this property.


Using size

var mySet = new Set();
mySet.add('some text')

mySet.size; // 3


Specification Status Comment
ECMAScript 2015 (6th Edition, ECMA-262)
The definition of 'Set.prototype.size' in that specification.
Standard Initial definition.
ECMAScript Latest Draft (ECMA-262)
The definition of 'Set.prototype.size' in that specification.
Living Standard  

Browser compatibility

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic support381219111258
FeatureAndroid webviewChrome for AndroidEdge mobileFirefox for AndroidIE mobileOpera AndroidiOS Safari
Basic support38381219111258

1. From Firefox 13 to Firefox 18, the size property was implemented as a Set.prototype.size() method, this has been changed to a property in later versions conform to the ECMAScript 2015 specification.

See also

Document Tags and Contributors

 Contributors to this page: fscholz, jameshkramer, nmve, kdex, Zambonifofex, realityking
 Last updated by: fscholz,