Binary Search in JS

binarySearch.js

function binarySearch(searchFor, arr, index1, index2) {
    if(index1 === undefined) index1 = 0;
    if(index2 === undefined) index2 = arr.length-1;
    var search = index1+Math.floor((index2-index1)/2);
    if(arr[search] == searchFor) return true;
    else if(index2-index1 <= 1) return false;
    else return binarySearch(searchFor, arr, arr[search] > searchFor ? index1 : search, arr[search] > searchFor ? search : index2);
}
var found = binarySearch(4, [1,3,6,9,12,17,25,44]);