解出来了。。。。 Array.prototype.reduceDepth(depth){     if(!depth){         depth = 1;     }     var newArr=[];     var currArr = this;     function pushArr(currArr,t){         var count = t+1;         for(var i = 0;i<currArr.length;i++){             if(currArr[i]==undefined){                 continue;             }             if(Array.isArray(currArr[i])){                 if(count > depth){                     return newArr.push(arr[i]);                 }                 fun(arr[i],count);             }else{                 newArr.push(currArr[i]);             }         }     }     pushArr(currArr,0);     return newArr; }