The keys()
method returns a new Iterator
object that contains the keys for each element in the Map
object in insertion order.
myMap.keys()
A new Map
iterator object.
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
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 |
Feature | Chrome | Edge | Firefox | Internet Explorer | Opera | Safari |
---|---|---|---|---|---|---|
Basic support | 38 | 12 | 20 | No | 25 | 8 |
Feature | Android webview | Chrome for Android | Edge mobile | Firefox for Android | Opera Android | iOS Safari | Samsung Internet |
---|---|---|---|---|---|---|---|
Basic support | 38 | 38 | 12 | 20 | 25 | 8 | ? |
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https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map/keys