Function binarySearch

src/searching/binarysearch.js:24–42

* Searches for specific element in a given array using * the binary search algorithm. * Time complexity: O(log N). * * @example * * var search = require('path-to-algorithms/src/searching/'+ * 'binarysearch').binarySearch; * console.log(search([1, 2, 3, 4, 5], 4)); //

(array, value, key)

   * @returns {Number} Index of the element or -1 if not found.
   */
  function binarySearch(array, value, key) {
    key = !key ? id : typeof key === 'string' ? get(key) : key;
    value = key(value);
    var middle = Math.floor(array.length / 2);
    var left = 0;
    var right = array.length;
    while (right >= left) {
      var middleValue = key(array[middle]);
      if (middleValue === value) {
        return middle;
      } else if (middleValue > value) {
        right = middle - 1;
      } else {
        left = middle + 1;
      }
      middle = Math.floor((left + right) / 2);
    }
    return -1;
  }

  exports.binarySearch = binarySearch;