Remove Duplicate Items from an Array in JavaScript

JavaScript has a very powerful built-in Set object that is used for storing unique values, regardless of type. For example, we can use Set to remove all the duplicate items from a given array:

const removeDuplicates = (array) => {
    return [...new Set(array)];
};

The removeDuplicates function could be used like this:

const oldArray = [1, 1, 2, 2, 3, 3];

const newArray = removeDuplicates(oldArray);

After the above code has executed, newArray will equal [1, 2, 3]. This is just oldArray but without the duplicate items.

If there weren’t any duplicate items, then the returned value for newArray would be identical to the value of oldArray.

One-liner to remove duplicates

This is a one-liner variant of our removeDuplicates function with the exact same behavior:

const removeDuplicates = (array) => [...new Set(array)];

Conclusion

As much as I’d like to talk more about the Set object and its massive versatility, I’ll wrap this up before I get carried away.

Anyway, I hope this article helped you with removing your duplicate array items!