Remove duplicated arrays is a common task in Javascript, in the next post we will see many ways to overcome to this situation, from simpler and modern to classic old ones

1.Using Set (recommended)

Set allows us to store the unique values, so converting a normal array with duplicated values using Set is the most easy and fastest solution.

const array = [1, 2, 3, 4, 4, 5, 5, 6];
const uniqueArray = [...new Set(array)];
console.log(uniqueArray); // [1, 2, 3, 4, 5, 6]

2.Using filter and indexOf

Another way of removing duplicated values is using filter and indexOf for checking its index, so this is used to be sure that the element only appears once.

const array = [1, 2, 3, 4, 4, 5, 5, 6];
const uniqueArray = array.filter((item, index) => array.indexOf(item) === index);
console.log(uniqueArray); // [1, 2, 3, 4, 5, 6]

3.Using reduce

We can use the method reduce to store the elements in uniques in a new array.

const array = [1, 2, 3, 4, 4, 5, 5, 6];
const uniqueArray = array.reduce((acc, item) => {
  if (!acc.includes(item)) {
    acc.push(item);
  }
  return acc;
}, []);
console.log(uniqueArray); // [1, 2, 3, 4, 5, 6]

4.Using forEch and Object

Another way could be using forEach for iterate over the array and using Objct for storing the unique values, then convert the keys of the Object to an array again.

const array = [1, 2, 3, 4, 4, 5, 5, 6];
const uniqueObj = {};
array.forEach((item) => {
  uniqueObj[item] = true;
});
const uniqueArray = Object.keys(uniqueObj).map(Number);
console.log(uniqueArray); // [1, 2, 3, 4, 5, 6]

The good ✅ and the bad ❌

Método	Ventajas	Desventajas
Set	Simple and efficient	No support for older versions of IE
filter and indexOf	Easy to understand	Not suitable for big arrays
reduce	Useful and functional	Complex for reading
forEch	Easy to understand and implement	Too much code and inefficient

Conclusion

Me as a programmer I use the Set method because of readability, performance and because in my job we don’t support old browsers like IE o Netscape