JavaScript 二分查找算法实现与示例

<!DOCTYPE html>
<html>
  <head>
    <title>demo</title>
    <style type="text/css">
    </style>
    <script type="text/javascript">
      var binarySearch = function(array, start, stop, num) {
        if(stop - start == 1) {
          if(array[start] == num) {
            return start;
          }
          if(array[stop] == num) {
            return stop;
          }
          return -1;
        }  
        var center = Math.floor((start + stop)/2);
        if(num != array[center]) {
          return num > array[center] ? binarySearch(array, center, stop, num) 
            : binarySearch(array, start, center, num);
        }
        return center;
      }
      var array = [1,4,6,12,15,20];
      document.writeln(binarySearch(array, 0, array.length, 2));
    </script>
  </head>
  <body>
  </body>
</html>