The set.keys() method is the same as the values() method. This means it returns the new iterator object that contains the value of each set in the insertion order. 

Syntax:

keys()

Parameter: This method does not take any parameters.

Return Type: It returns the new iterator object which holds the values in the set.

Example 1: In this example, we will see the use of keys in the set.

let placeSet = new Set();

placeSet.add("America");
placeSet.add("England");
placeSet.add("Chicago");

const setIterator = placeSet.keys();

console.log(setIterator);

Output:

[Set Iterator] { 'America', 'England', 'Chicago' }

Example 2: In this example, we will see the keys() method which returns the set iterator.

const set1 = new Set();

set1.add('0');
set1.add(1);
set1.add(1);

const iterator1 = set1.keys();
console.log(iterator1);

[Set Iterator] { '0', 1 }

We have a complete list of Javascript Set methods, to check those please go through this Sets in JavaScript article.

Supported Browser:

• Chrome 38
• Edge 12
• Firefox 24
• Opera 25
• Safari 8

FAQs – JavaScript Set keys() Method

Can the iterator returned by Set.keys() be used in a for…of loop?

Yes, the iterator returned by Set.keys() can be used in a for…of loop to iterate over the values of the Set.

Does Set.keys() preserve the insertion order of elements?

Yes, Set.keys() preserves the insertion order of elements in the Set.

What happens if you modify the Set while iterating with Set.keys()?

If you modify the Set while iterating with Set.keys(), the iterator will reflect the changes. Elements added after the iterator is created may or may not be visited, depending on the browser’s implementation.

Can Set.keys() be used on other collection types?

No, Set.keys() is specific to Set objects. Other collection types like Map have their own keys() methods.

What is the result of calling Set.keys() on an empty Set?

The iterator returned by Set.keys() will be empty, and iterating over it will produce no values.