js去除数组中重复的数字

var arr = [2,1,4,3,2,4,2,3,4,2,6,5,5]
var obj = {};
var arrNew = [];
for(var i=arr.length-1;i>=0;i--){
if(!obj[arr[i]]){
obj[arr[i]] = true;
arrNew.push(arr[i]);
}
}
console.log(arrNew,obj)
// [5, 6, 2, 4, 3, 1]

Array.prototype.unique2 = function(){
this.sort(); //先排序
var res = [this[0]];
for(var i = 1; i < this.length; i++){
if(this[i] !== res[res.length - 1]){
res.push(this[i]);
}
}
return res;
}
var arr = [1, 'a', 'a', 'b', 'd', 'e', 'e', 1, 0]
console.log(arr.unique2());