BinarySearch.js

/* Returns either the index of the location in the array,
  or -1 if the array did not contain the targetValue */
var doSearch = function(array, targetValue) {
	var min = 0; 
	var max = array.length - 1;
    var guess;
    var num=0;
    while(min <= max ){
        num++;
        guess = Math.floor((min + max)/2);
        println("You gussed : "+guess);
        if(array[guess]  < targetValue){ min =guess +  1; }
        else if(array[guess]  > targetValue){  max=guess -1;  }
        else {  println(num);  return guess;  }
    }
	return -1;
};  



var primes = [2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97];

var result = doSearch(primes, 73);  
println("Found prime at index " + result);
Program.assertEqual(doSearch(primes, 73), 20);
Program.assertEqual(doSearch(primes, 41), 12);

Program.assertEqual(doSearch(primes, 2), 0);



url: https://www.khanacademy.org/computing/computer-science/algorithms/binary-search/p/challenge-binary-search