The JavaScript map keys() method is used to retrieve an object of the Map iterator that contains the keys for each element.
Syntax:
mapObj.keys()
Return:
An object of Map iterator.
Example:
<!DOCTYPE html>
<html>
<body>
<script>
var hello=new Map();
hello.set('a',"GOOD MORNING");
hello.set('b',"GOOD AFTERNOON");
hello.set('c',"GOOD EVENING");
hello.set('d',"GOOD NIGHT");
var array= hello.keys();
document.writeln(array.next().value+"<br>");
document.writeln(array.next().value+"<br>");
document.writeln(array.next().value+"<br>");
document.writeln(array.next().value);
</script>
</body>
</html>