What are the different ways to remove duplicates from an ES6 array object?

2 years ago
Liam
2 minutes

In ES6, there are several methods to remove duplicates from an array object:

  1. Using Set: Set is a new data structure introduced in ES6 which ensures that the elements in the collection are unique. You can use Set to remove duplicate items from an array and then convert the Set back to an array. Example code is as follows:
const arr = [1, 2, 3, 3, 4, 5, 5];
const uniqueArr = [...new Set(arr)];
console.log(uniqueArr); // [1, 2, 3, 4, 5]
  1. Use Array.from() and Set: You can first convert an array to a Set using Array.from(), and then convert the Set back to an array. Example code is shown below:
const arr = [1, 2, 3, 3, 4, 5, 5];
const uniqueArr = Array.from(new Set(arr));
console.log(uniqueArr); // [1, 2, 3, 4, 5]
  1. You can use the filter() method to iterate through an array, keeping only the first occurrence of an element and filtering out any duplicates that follow. Here is an example code snippet:
const arr = [1, 2, 3, 3, 4, 5, 5];
const uniqueArr = arr.filter((item, index) => arr.indexOf(item) === index);
console.log(uniqueArr); // [1, 2, 3, 4, 5]
  1. With the use of the reduce() method, you can iterate through an array, add each element to a result array, but only add the element the first time it appears and filter out any subsequent duplicate occurrences. See the example code below:
const arr = [1, 2, 3, 3, 4, 5, 5];
const uniqueArr = arr.reduce((result, item) => {
  if (!result.includes(item)) {
    result.push(item);
  }
  return result;
}, []);
console.log(uniqueArr); // [1, 2, 3, 4, 5]

These methods are all effective ways to deduplicate array objects.

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