Working with Sets

Working With Sets

Checking The Length

Once you’ve constructed your Set, there are a couple of different properties and methods you can use to work with Sets.

Use the.sizeproperty to return the number of items in a Set:

const months = new Set(['January', 'February', 'March', 'April', 'May', 'June',
                        'July', 'August', 'September', 'October', 'November', 'December']);
console.log(months.size);

12

Remember, Sets can’t be accessed by their index like an array, so you use the.sizeproperty instead of.lengthproperty to get the size of the Set.

Checking If An Item Exists

Use the.has()method to check if an item exists in a Set. If the item is in the Set, then.has()will returntrue. If the item doesn’t exist in the Set, then.has()will returnfalse.

console.log(months.has('September'));

true

Retrieving All Values

Finally, use the.values()method to return the values in a Set. The return value of the.values()method is aSetIteratorobject.

console.log(months.values());

SetIterator {'January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December'}

More on theSetIteratorobject in a second!

TIP: The.keys()method will behave the exact same way as the.values()method by returning the values of a Set within a new Iterator Object. The.keys()method is an alias for the.values()method for similarity with maps. You’ll see the.keys()method later in this lesson during the Maps section.