Gives values of array not present in another.
Similar: union, intersection, difference, symmetricDifference.
This is part of package extra-array.
array.difference(x, y, [fc], [fm]);
// x: an array
// y: another array
// fc: compare function (a, b)
// fm: map function (v, i, x)
⏱️ Compare function => O(n²).
const array = require("extra-array");
var x = [1, 2, 3, 4, 5];
var y = [2, 4];
array.difference(x, y);
// [ 1, 3, 5 ]
var y = [-2, -4];
array.difference(x, y);
// [ 1, 2, 3, 4, 5 ]
array.difference(x, y, (a, b) => Math.abs(a) - Math.abs(b));
// [ 1, 3, 5 ]
array.difference(x, y, null, v => Math.abs(v));
// [ 1, 3, 5 ]