shift.html

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

/* Prototype function
    function shift(originalArray) {
        var returnElement = originalArray[0];
        for(var i = 0; i < originalArray.length; i++) {
          originalArray[i] = originalArray[i+1];
        }
        delete originalArray[originalArray.length];
        originalArray.length--;
        return returnElement;
    }
*/

function shift(originalArray) {
      if(originalArray.length === 0) return undefined;
      var returnElement = originalArray[0];
      for(var i = 0; i < originalArray.length; i++) {
        originalArray[i] = originalArray[i+1];
      }
      delete originalArray[originalArray.length];
      originalArray.length--;
      return returnElement;
    }


tests({

  'It should return the removed element': function () {
    var testArray = [1,2,3];
    var returnResult = shift(testArray);
    eq(returnResult,1);
  },

  'It should modify the original array': function () {
    var testArray = [1,2,3];
    var returnResult = shift(testArray);
    eq(testArray[2],undefined);
  },

  'It should shorten the original array by 1': function () {
    var testArray = [1,2,3];
    var returnResult = shift(testArray);
    eq(testArray.length,2);
  },

  'It should return undefined for an empty array': function () {
    var testArray = [];
    var returnResult = shift(testArray);
    eq(returnResult,undefined);
  },

  'It should return the element at the zero index': function () {
    var testArray = [1,2,3];
    var returnResult = shift(testArray);
    eq(returnResult,1);
  },

  'It should shift the remaining elements indices by -1': function () {
    var testArray = [1,2,3];
    var returnResult = shift(testArray);
    eq(testArray.indexOf(2),0);
    eq(testArray.indexOf(1),-1)
  }
});

</script>