The keys() method returns a new Iterator object that contains the keys for each element in the Map object in insertion order.

Syntax

myMap.keys()

Return value

A new Map iterator object.

Examples

Using keys()

var myMap = new Map();
myMap.set('0', 'foo');
myMap.set(1, 'bar');
myMap.set({}, 'baz');

var mapIter = myMap.keys();

console.log(mapIter.next().value); // "0"
console.log(mapIter.next().value); // 1
console.log(mapIter.next().value); // Object

Specifications

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

Browser compatibility

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic support381220 No258
FeatureAndroid webviewChrome for AndroidEdge mobileFirefox for AndroidIE mobileOpera AndroidiOS Safari
Basic support38381220 No258

See also

Document Tags and Contributors

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