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. |
Draft |
Browser compatibility
Feature | Chrome | Edge | Firefox (Gecko) | Internet Explorer | Opera | Safari |
---|---|---|---|---|---|---|
Basic support | 38 | (Yes) | 20 (20) | No support | 25 | 7.1 |
Feature | Android | Chrome for Android | Edge | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile |
---|---|---|---|---|---|---|---|
Basic support | No support | 38 | (Yes) | 20.0 (20) | No support | No support | 8 |