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Removing duplicated items in array with Set

12 January 2023

Removing duplicates from an array is a common task in JavaScript, and there are a few different ways to do it. One simple way is to use the Set object.

A Set is a collection of unique values. When you add a value to a set, it will only be added if it doesn't already exist in the set. This means that if you add an array of values to a set, any duplicates will be automatically removed.

Here's some example code:

// Array with duplicates
const numbers = [1, 2, 3, 4, 4, 5, 5, 6]
// Create a new Set from the array
const uniqueNumbers = new Set(numbers)
console.log(uniqueNumbers) // Set { 1, 2, 3, 4, 5, 6 }

You can also convert the set back to an array if that's the format you need:

const uniqueNumbersArray = [...uniqueNumbers]
console.log(uniqueNumbersArray) // [1, 2, 3, 4, 5, 6 ]

If it's a repeating task in your code, you can create a function for it:

function removeDuplicates(list) {
  const set = new Set(list)
  return [...set]