Simplest ‘getUniqueValues’ in JavaScript arrays

I’ve been finding this question a lot in job interview exercises, and I always take more time than I should to solve it because I keep forgetting how to do it.

This might not be the best/fastest solution, but it’s the simplest I’ve found to do it:

[…].filter(function (val, idx, arr) {
    return arr.indexOf(val) === arr.lastIndexOf(val);
});