myReverse.html

haha<script src="..\my-jsArrayMethods\simpletest.js"></script>
<script>
  // The reverse() method reverses an array in place. 
    // The first array element becomes the last, and the last array element becomes the first.
  // Notes:
    // The reverse method transposes the elements of the calling array object in place, 
    // mutating the array, and returning a reference to the array.
    // myReverse will throw an error if not passed an array.
  
  function myReverse(arr) {
    if(!Array.isArray(arr)) {
      throw new TypeError('myReverse must be passed an array.')
    }
    var halfLength = Math.floor(arr.length/2);
    for (var i = 0; i < halfLength; i++) {
      var originalValue = arr[i];
      var swapIndex = arr.length - 1 - i;
      var swapValue = arr[swapIndex];

      arr[i] = swapValue;
      arr[swapIndex] = originalValue;
    }
    return arr;
  }

  tests({
    'It should return a reference to the input array.': function() {
      myArray = [1, 2, 3];
      eq(myReverse(myArray), myArray);
    },
    'It should throw type error if not passed an array.': function() {
      var isTypeError = false;
      try {
        myReverse({});
      }
      catch(e) {
        isTypeError = (e instanceof TypeError);
      }
      eq(isTypeError, true);
    },
    'It should reverse the order of the elements in the array.': function() {
      var reversedArr = myReverse([1, 2, 3, 4, 5]);
      eq(reversedArr[0], 5);
      eq(reversedArr[4], 1);
    },
  })
</script>