JavaScript Sets

Abdelrahman Mohamed — Wed, 08 Mar 2023 01:59:09 +0000

Set is one of the new Data Structures that got added to JS with ES6.

Sets are not ordered like array but iterable
Sets can only have unique values even if we added duplicate values

//we can create sets like this
const mySet = new Set([1, 2, 2, 5, 5]);
const mySet2 = new Set(['pizza','pasta', 'fries','burger','pizza', 'cheese']);
const mySet3 = new Set('abdelrahman');
console.log(mySet,mySet2,mySet3);
//Set(3) {1, 2, 5}  //no duplicates
//Set(5) {'pizza', 'pasta', 'fries', 'burger', 'cheese'}
//Set(9) {'a', 'b', 'd', 'e', 'l', 'r','h','m','n'}

We can get set size like that
size of the unique values only

console.log(mySet.size); //3

we can also check element is in the set or not

console.log(mySet.has(2));//true 
console.log(mySet2.has('milk'));//false

we can add and delete values from a Set

mySet.add(10);
mySet.delete(2);
console.log(mySet);//{1, 5, 10}

there is no way of retrieving values from a set that’s because if all values are unique and if their does not matter there is no point of retrieving values out of a set and if your goal is to actually store values in order then the best use case is an Array
we can iterate over a set cause they are iterable as we said before

for(const item of mySet) console.log(item);
// 1
// 5
// 10

the main use cause of sets is actually to remove duplicate values from arrays

const arr = [10,10,20,20,30];
const uniqueArr = new Set(arr);
console.log(uniqueArr); //{10, 20, 30}

//if u want to save the unique values to an array again u can use the spread operator like that cause it work on all iterables
const uniqueArr = [...new Set(arr)];
console.log(uniqueArr); //[10, 20, 30]

and finally u can delete all set element by using clear method

arr.clear();

Forem: Abdelrahman Mohamed

JavaScript Sets