Array.prototype.unique (quit fast)

Array.prototype.unique = function () {
        var arr = this, newArr = [], obj = {};
        for(var i = 0, len = arr.length; i < len; i++){
            if (obj[arr[i]]) {
                        continue;
                }
                obj[arr[i]] = 1;
                newArr.push(arr[i]);
        }
        return newArr;
    };