map.keys

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 2017 Draft (ECMA-262) The definition of 'Map.prototype.keys' in that specification.	Draft

Browser compatibility

See also

• Map.prototype.entries()
• Map.prototype.values()