js数组去重

Array.prototype.myDistinct = function () {
        //this-->ary
        var obj = {};
        for (var i = 0; i < this.length; i++) {
            var cur = this[i];
            if (obj[cur] == cur) {
                this[i] = this[this.length - 1];
                this.length = this.length - 1;
                i--;
                continue;
            }
            obj[cur] = cur;
        }
        obj = null;
        return this;
    }
    var ary = [12, 23, 23, 12, 24, 34, 12];
    console.log(ary.myDistinct());