javascript-binarySearch

前提： 数组已排序，且为正整数数组.

 1 function brnarySearch(arg, arr) {
 2     var right = arr.length - 1;
 3     var left = 0;
 4     while(left <= right) {
 5           var mid = left + parseInt( (right - left) / 2 );
 6           if(arg < arr[mid]) right = mid - 1;
 7           else if(arg > arr[mid]) left = mid + 1;
 8           else return mid;
 9     }
10     return -1;
11 }
12 var arr = [1, 3, 5, 7, 9, 11, 12, 44, 56];
13 console.log(brnarySearch(9, arr));