Binary search in JavaScript

binary-search-javascript.js

/**
 * Binary search in JavaScript.
 *
 * For detailed explanation about binary search
 * read my original blog post:
 * http://www.nickang.com/binary-search-javascript/
 */

function binarySearch(array, key) {
    var lower = 0;
    var upper = array.length - 1;
    var mid;
    var currentItem;
    
    while (lower <= upper) {
        mid = Math.floor((lower + upper) / 2, 10);
        currentItem = array[mid];
        
        if (currentItem < key) {
            lower = mid + 1;
        } else if (currentItem > key) {
            upper = mid - 1;
        } else {
            return mid;
        }
    }
    return -1;
}

// test it
var input = [0, 2, 40, 44, 48, 55, 66, 99];
console.log(binarySearch(input, 66));  // should print 6