• Russian version

Array intersection, difference and union in ES6

For all the examples, we have two arrays, A let arrA=[1,3,4,5] & B let arrB=[1,2,5,6,7]

Intersection

The intersection will give us the elements that both arrays share in common, in this case the result must be [1,5].

let intersection = arrA.filter(x => arrB.includes(x));

Difference

The difference will output the elements from array A that are not in the array B. The result will be [3,4].

let difference = arrA.filter(x => !arrB.includes(x));

Symmetrical Difference

In this case, you will get an array containing all the elements of arrA that are not in arrB and vice-versa, so the result should be [2,3,4,6,7].

let difference = arrA.filter(x => !arrB.includes(x)).concat(arrB.filter(x => !arrA.includes(x)));

Union

The union must be the simplest of them all, at the end, the result should be all the elements from A, all from B, or both like this [1,2,3,4,5,6,7].

let union = [...arrA, ...arrB];

But, there is a problem is that if we use spread operator, we will get elements duplicated, so it’s no theoretically an union. For doing this we have can use a Set to help us out:

let union = [...new Set([...arrA, ...arrB])];