js快速排序

function sort(arr){
    if(arr.length<=1){
       return arr;
     }
     var num = Math.floor(arr.length/2);
     var numValue = arr.splice(num,1);
     var left = [];
     var right = [];
     for(var i = 0; i < arr.length; i++){
           if(arr[i]<numValue){
               left.push(arr[i]);
            }else{
               right.push(arr[i]);
            }
      }
      return sort(left).concat([numValue],sort(right));
}

alert(sort([12,6,5,37,40]));