/* 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;
    while(max>=min){
        guess = Math.floor((max+min)/2);
        if(array[guess]===targetValue){return guess;}
        else if(array[guess]<targetValue){min=guess+1;}
        else{max=guess-1;}
    }
	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);