reverse.html

<script src="../simpleTest.js"></script>
<script>

// MDN Definition:
// The reverse() method reverses an array in place. 
// The first array element becomes the last, and the last 
// array element becomes the first.

// NOTES:


// reverse REQUIREMENTS:
// DONE It should reverse the entire array.
// DONE It should mutate the array, not create a new array.
// DONE It should return the reversed array.
// It should reverse the array in place.
  // I think this means it should return the same array, looking into this.



/*
function reverse(array) {
  var copyArray = array;
  var bucket = [];

  if (typeof arguments[0] !== 'object') {
    throw new TypeError('array.reverse is not a function');
  }

  for (var i = array.length - 1; i >= 0; i--) {
    bucket.push(copyArray[i]);
  }
  for (var j = 0; j < bucket.length; j++) {
    array[j] = bucket[j];
  }
  return array;
}
*/

// This one should be "in place"
// The above one also works but uses another array to transfer the order over to the original array.
function reverse(array) {
  if (typeof arguments[0] !== 'object') {
    throw new TypeError('array.reverse is not a function');
  }

  array.length = array.length * 2;
  var compliment = 0;

  for (var i = array.length - 1; i >= array.length / 2; i--) {
    array[i] = array[compliment];
    compliment++;
  }
  for (var j = 0; j < array.length / 2; j++) {
    array[j] = array[(array.length / 2) + j]
  }

  array.length = array.length / 2;

  return array;
}




tests({

  'It should reverse the entire array.': function() {
    var myArray = ['first', 'second'];
    reverse(myArray);
    eq(myArray, 'second,first');
  },
  'It should mutate the array.': function() {
    var myArray = [1, 2];
    var result = reverse(myArray);
    eq(result, myArray);
  },
  'It should return the reversed array.': function() {
    var myArray = [1, 2];
    var result = reverse(myArray);
    eq(result, '2,1');
    eq(result, myArray);
  },
  'If the element passed in is not an object, it should throw a TypeError': function() {
    var isTypeError = false;
    try {
      reverse(2);
    } catch(e) {
      isTypeError = (e instanceof TypeError);
    }
    eq(isTypeError, true);
  }


});
</script>