如何消除一个数组里面重复的元素？

         var arr=[1,2,3,3,4,4,5,5,6,1,9,3,25,4];
         function deRepeat(){
             var newArr=[];
             var obj={};
             var index=0;
             var l=arr.length;
             for(var i=0;i<l;i++){
                 if(obj[arr[i]]==undefined)
                   {
                     obj[arr[i]]=1;
                     newArr[index++]=arr[i];
                  }
                 else if(obj[arr[i]]==1)
                   continue;
             }
             return newArr;
 
         }
         var newArr2=deRepeat(arr);
         alert(newArr2); //输出1,2,3,4,5,6,9,25