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 counter = 0;
      while(max >= min){
          guess = Math.floor((min + max) / 2);
          println(guess);
          counter++;
          if (array[guess] === targetValue) {
              println("It took "+counter+" interations to find the target value");
          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);
  Program.assertEqual(doSearch(primes, 31), 10);
  Program.assertEqual(doSearch(primes, 3), 1);