Quickest way to check if 2 arrays contain same values in javascript

Question

Is there a quicker or more efficient way to check that two arrays contain the same values in javascript?

Here is what I'm currently doing to check this. It works, but is lengthy.

    var arraysAreDifferent = false;
    for (var i = 0; i < array1.length; i++) {
      if (!array2.includes(array1[i])) {
        arraysAreDifferent = true;
      }
    }
    for (var i = 0; i < array2.length; i++) {
      if (!array1.includes(array2[i])) {
        arraysAreDifferent = true;
      }
    }

Answer 1

To reduce computational complexity from O(n ^ 2) to O(n), use Sets instead - Set.has is O(1), but Array.includes is O(n).

Rather than a regular for loop's verbose manual iteration, use .every to check if every item in an array passes a test. Also check that both Set's sizes are the same - if that's done, then if one of the arrays is iterated over, there's no need to iterate over the other (other than for the construction of its Set):

const arr1Set = new Set(array1);
const arr2Set = new Set(array2);
const arraysAreDifferent = (
  arr1Set.size === arr2Set.size &&
  array1.every(item => arr2Set.has(item))

);