binarySearch.js

/**
 * 二分查找
 * @param {Array}  array - 有序数组
 * @param {Number} value - 查找目标值
 */
function binarySearch (array, value) {
  let index = 0;
  let left  = 0;
  let right = array.length - 1;
  while (left < right) {
    index = Math.floor(left + (right - left) / 2);
    if (value > array[index]) {
      left = index + 1;
    } else {
      right = index;
    }
  };
  if (value === array[right]) {
    return right;
  }
  return -1;
}