javascript instance method
Map.prototype.keys()
The keys() method of Map instances returns a new map iterator object that contains the keys for each element in this map in insertion order.
Interactive exampleOpen the canonical MDN source to run this embedded demo.
const map = new Map();
map.set("0", "foo");
map.set(1, "bar");
const iterator = map.keys();
console.log(iterator.next().value);
// Expected output: "0"
console.log(iterator.next().value);
// Expected output: 1
Syntax
keys()
Parameters
None.
Return value
A new iterable iterator object.
Examples
Using keys()
const myMap = new Map();
myMap.set("0", "foo");
myMap.set(1, "bar");
myMap.set({}, "baz");
const mapIter = myMap.keys();
console.log(mapIter.next().value); // "0"
console.log(mapIter.next().value); // 1
console.log(mapIter.next().value); // {}
Specifications
SpecificationsStandards references are available on the canonical MDN page.
Browser compatibility
Browser compatibilityCompatibility data is available on the canonical MDN page.