Binary Search Algorithm

binary_search.js

/**
 * @param {list} data List of integers sorted ascending
 * @param {int} find Integer to search for
 * @param {int} start Min array index
 * @param {int} end Max array index
 * @return {int} Index of 'find' or -1 if not found
*/
var binarySearch = function (data, find, start, end) {

    var mid = start + (end - start) / 2;

    if (start > end) {
        return -1;
    } else if (data[mid] == find) { // Found it
        return mid;
    } else if (data[mid] > find) { // mid is greater than find, search lower half
        return binarySearch(data, find, start, mid - 1);
    } else { // mid is less than find, search upper half
        return binarySearch(data, find, mid + 1, end);
    }
}

binary_search.py

def binarySearch(data, find, start, end):
    """
    Search for a integer in a list of integers using a simple `Binary Search` algorithm

    :param list data: list of integers sorted ascending
    :param int find: integer to search for
    :param int start: min array index
    :param int end: max array index
    :return int: index of 'find' or -1 if not found
    """
    mid = start + (end - start) / 2 # find mid point between start and end

    if start > end:
        return -1
    elif data[mid] == find: # found it
        return mid
    elif data[mid] > find: # mid index is greater than find, search lower half
        return binarySearch(data, find, start, mid - 1)
    else: # mid index is less than find, search upper half
        return binarySearch(data, find, mid + 1, end)