JavaScript Map keys() method is used to extract the keys from a given map object and return the iterator object of keys.
obj.keys() This method returns an object of a new Map iterator. This object contains the key for each element. It maintains insertion order.
JavaScript Map keys
Simple example code.
<!DOCTYPE html>
<html>
<body>
<script >
var map = new Map();
map.set(1,"ABC");
map.set(2,"XYZ");
map.set(3,"PQR");
var itr = map.keys();
console.log(itr.next().value);
console.log(itr.next().value);
console.log(itr.next().value);
console.log(itr.next().value);
</script>
</body>
</html>Output:
More example 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); // ObjectUsing for loop
<script >
var map = new Map();
map.set(1,"ABC");
map.set(2,"XYZ");
map.set(3,"PQR");
var itr = map.keys();
for(i=0;i<map.size;i++)
{
console.log(itr.next().value);
}
</script>Do comment if you have any doubts or suggestions on this Js map method tutorial.
Note: The All JS Examples codes are tested on the Firefox browser and the Chrome browser.
OS: Windows 10
Code: HTML 5 Version