Get the Difference between Two Sets using JavaScript

To get the difference between two sets in JavaScript, you need to identify elements present in the first set but not in the second. This involves iterating over the first set and filtering out elements that are also found in the second set, ensuring efficient comparison.

We can get the difference between two sets using Javascript by the following methods:

Approach 1: Use the filter() method

• Store both array values in the two variables.
• Use the filter() method for every value of array_1, if there is a value in array_2 then do not include it. Otherwise include the value of array_1.

Example 1: In this example, the set difference is calculated using the filter() method. 

let A = [7, 2, 6, 4, 5];
let B = [1, 6, 4, 9];

function GFG_Fun() {
    let diff = A.filter(x => !B.includes(x))
    console.log("Set-Difference: " + diff);
}

GFG_Fun();

Set-Difference: 7,2,5

Example 2: In this example, the set difference is calculated using the filter() method but by a bit different approach. 

 A = ["GFG", "GeeksForGeeks", "a", "b"];
 B = ["gfg", "a", "b"];

function GFG_Fun() {
    diff = A.filter(function (x) {
        return B.indexOf(x) < 0
    })

    console.log("Set Difference: " + diff);
}

GFG_Fun();

Set Difference: GFG,GeeksForGeeks

Approach 2: Using Set delete() Method

The Set.delete() method in JavaScript is used to delete an element with a specified value in a set and returns a boolean value depending upon the availability of the element.

Example:

let A = [7, 2, 6, 4, 5];
let B = [1, 6, 4, 9];
const set1 = new Set(A);
const set2 = new Set(B);

const difference = new Set(set1);
for (const element of set2) {
    difference.delete(element);
}
console.log([...difference]);

[ 7, 2, 5 ]

Approach 3: Using Set forEach() Method

The set.forEach() method is used to execute the function which is taken as a parameter and applied for each value in the set, in insertion order.

Example:

let A = [7, 2, 6, 4, 5];
let B = [1, 6, 4, 9];
const set1 = new Set(A);
const set2 = new Set(B);

const difference = new Set();
set1.forEach(element => {
    if (!set2.has(element)) {
        difference.add(element);
    }
});
console.log([...difference]);

[ 7, 2, 5 ]