Map.prototype.keys()

The keys() method returns a new iterator object that contains the keys for each element in the Map object in insertion order. In this particular case, this iterator object is also an iterable, so a for...of loop can be used.

Try it

Syntax

keys();

Return value

A new Map 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); // Object

Specifications

Specification
ECMAScript Language Specification
# sec-map.prototype.keys

Browser compatibility

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See also