JavaScript binary search algorithm

binary-search.js

function binarySearch(list, item) {
  var low = 0;
  var high = list.length - 1;

  while (low <= high) {
    var mid = low + Math.floor((low + high) / 2);
    var guess = list[mid];

    if (guess === item) {
      return mid;
    }

    if (guess > item) {
      high = mid - 1;
    } else {
      low = mid + 1;
    }
  }

  return -1;
}