Removes duplicate values.
Similar: union, intersection, difference, unique, isUnique, isDisjoint.
This is part of package extra-array.
array.unique(x, [fc], [fm]);
// x: an array
// fc: compare function (a, b)
// fm: map function (v, i, x)
ā±ļø Compare function => O(n²).
const array = require('extra-array');
var x = [1, 2, 3, 4, 2, 3];
array.unique(x);
// [ 1, 2, 3, 4 ]
var x = [1, 2, 3, 4, -2, -3];
array.unique(x, (a, b) => Math.abs(a) - Math.abs(b));
// [ 1, 2, 3, 4 ]
array.unique(x, null, v => Math.abs(v));
// [ 1, 2, 3, 4 ]