What is the fastest or most elegant way to compute a set difference using Javascript arrays?

October 18, 2022 by Tarik

I don’t know if this is most effective, but perhaps the shortest:

var A = [1, 2, 3, 4];
var B = [1, 3, 4, 7];

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

console.log(diff); // [2]

Updated to ES6:

const A = [1, 2, 3, 4];
const B = [1, 3, 4, 7];

const diff = A.filter(x => !B.includes(x));

console.log(diff); // [2]