Map.prototype.keys()

This is an experimental technology, part of the Harmony (ECMAScript 6) proposal.
Because this technology's specification has not stabilized, check the compatibility table for usage in various browsers. Also note that the syntax and behavior of an experimental technology is subject to change in future version of browsers as the spec changes.

Summary

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()

Examples

Example: 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 Language Specification 6th Edition (ECMA-262) Draft Initial definition.

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
Basic support Not supported 20 (20) Not supported Not supported Not supported
Feature Android Chrome for Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support Not supported Not supported 20.0 (20) Not supported Not supported Not supported

See also

Document Tags and Contributors

Contributors to this page: fscholz
Last updated by: fscholz,