How to get unique values in an array

Question

How can I get a list of unique values in an array? Do I always have to use a second array or is there something similar to java\'s hashmap in JavaScript?

I am going

Answer 1

Using jQuery, here's an Array unique function I made:

Array.prototype.unique = function () {
    var arr = this;
    return $.grep(arr, function (v, i) {
        return $.inArray(v, arr) === i;
    });
}

console.log([1,2,3,1,2,3].unique()); // [1,2,3]