Sets in Javascript

The set object lets you store unique values of any type, whether primitive values or object references.

Photo by timJ on Unsplash

Let’s talk about the fact that we have a series of numbers and that we don’t want repeated values, we just want unique values.

let numbers = [1, 25, 33, 1, 54, 3, 2, 15];

How do you remove the duplicates, we have a few options:

Foreach()

function removeDuplicates(numbers) {
    let unique = {};
    numbers.forEach(number => {
       if (!unique[number]) { 
          unique[number] = true;
       }
    });
 return Object.keys(unique);
}
console.log(removeDuplicates(numbers));
// [ '1', '2', '3', '15', '25', '33', '54' ]

Filter()

let numbers = [1, 25, 33, 1, 54, 3, 2, 15];
let newNumbers = numbers.filter((number, index) => {
     return numbers.indexOf(number) === index;
});
console.log(newNumbers);
// [ 1, 25, 33, 54, 3, 2, 15 ]

But the most simple option is,

new Set( [iterable] );

This object have one argument (iterable)

iterable -> Optional. If an iterable object is passed, all of its elements will be added to the new Set. If you don't specify this parameter, or its value is null, the new Set is empty.

Let´s remove the duplicates with Set Object and also convert the set into an array:

let numbers = [1, 25, 33, 1, 54, 3, 2, 15];
let numbersWithoutDuplicates = new Set(numbers);
console.log(Array.from(numbersWithoutDuplicates));
// [ 1, 25, 33, 54, 3, 2, 15 ]

You can find links to my other work on Medium and follow me here.

The function filter() in Javascript

The function map() in Javascript ES6

Reduce() in Javascript ES6

I often share more code tips on my Instagram you can say hello to me on my Twitter or see how i code in my Github.

Thank you very much and keep coding!!!

Yoel