二分查找 找到了返回位置 没找到返回应该插入的位置

  var arr = [1,4,6,12,17,19,44,66,71];
  function bisearch(arr,low, high, val){
    var mid = parseInt((low + high)/2) ;
    if(low <= high){
      if( arr[mid] == val){
        return mid;
      }else{
        if(arr[mid] < val){
          return bisearch(arr,mid+1,high,val);
        } else{
          return bisearch(arr,low,mid-1,val);
        }
      }
    }else{
      return low;
    }
  }
  console.log(bisearch(arr,0,arr.length-1,44));
  console.log(bisearch(arr,0,arr.length-1,55));