BinarySearch of an array

binarySearch.js

function binarySearch(array, key) {
    var lo = 0,
        hi = array.length - 1,
        mid,
        element;
    while (lo <= hi) {
        mid = Math.floor((lo + hi) / 2);
        element = array[mid];
        if (element < key) {
            lo = mid + 1;
            console.log(lo,"elment < key", mid, array[mid]);
        } else if (element > key) {
            hi = mid - 1;
            console.log(hi, "element > key", mid, array[mid]);
        } else {
            return mid;
        }
    }
    return -1;
}

var arr = [1,2,3,4,6,7,8,9,10,11,13,15,17,20];
binarySearch(arr, 2);