ECMAScript 2015 – the Set class

ECMAScript 2015 introduced a Set class as part of the JavaScript API. We developed our Set class based on the ES2015 Set class.

Note

You can see the details of the ECMAScript 2015 Set class implementation at https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Set (or http://goo.gl/2li2a5).

Now, let's take a look at how we can use the native Set class, as well.

Let's use the same examples we used to test our Set class, as follows:

const set = new Set(); 
set.add(1); 
console.log(set.values()); // outputs @Iterator 
console.log(set.has(1)); // outputs true 
console.log(set.size); // outputs 1 

The difference between our Set class and the ES2015 Set class is that the values method returns Iterator (which you learned in Chapter 3, Arrays) instead of the array with the values. Another difference is that we developed a size method to return the number of values the Set stores. The ES2015 Set class has a property named size.

We can also call...