数组排序去重

var arr = [1,2,34,3,55,48,1,34,55];

Array.prototype.unique = function(){
    //先排序
    this.sort((val1,val2)=>val2-val1)
    //创建结果数组
     var result = [this[0]];
    for(var i = 1; i < this.length; i++){
         if(result.indexOf(this[i]) == -1){
              result.push(this[i]);
         }
     }
    console.log(result)
    return result;
}
arr.unique();