includes.html

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

// MDN Definition:
// The includes() method determines whether an array includes a certain value 
// among its entries, returning true or false as appropriate.

// NOTES:


// includes REQUIREMENTS:

// DONE It should compare searchValue to each element in the array.
// DONE If the array includes the desired value, it should return true.
// DONE If the array does not include the desired value, it should return false.
// DONE If third argument is included, it should begin searching the array from the value of the third argument (startingIndex).
// DONE If startingIndex is negative, it should begin searching the array that many indexes from the end of the array.
// DONE It should return a boolean value.
// DONE If the calculated value of arr.length + startingIndex is less than 0, it should search entire array.
// DONE If startingIndex is greater than or equal to array.length, it should return false.


function includes(array, searchValue, startingIndex) {
  var result = false;
  var endOfArray = array.length;

  if (arguments.length > 2) {
    if (startingIndex > array.length) {
      result = false;
      return result;
    } else if (startingIndex < 0) {
      for (var k = endOfArray + startingIndex; k < array.length; k++) {
        if (array[k] === searchValue) {
          result = true;
          return result;
        }
      }
    } else {
      for (var j = startingIndex; j < array.length; j++) {
        if (array[j] === searchValue) {
          result = true;
          return result;
        }
      }
    }
  } else {
    for (var i = 0; i < array.length; i++) {
      if (array[i] === searchValue) {
        result = true;
        return result;
      }
    }
  }
  return result;
}

tests({

  'It should compare searchValue to each element in the array.': function() {
    var myArray = [1];
    var result = includes(myArray, 1);
    eq(result, true);
  },
  'If the array includes the desired value, it should return true.': function() {
    var myArray = [1];
    var result = includes(myArray, 1);
    eq(result, true);
  },
  'If the array does not include the desired value, it should return false.': function() {
    var myArray = [1];
    var result = includes(myArray, 2);
    eq(result, false);
  },
  'If third argument is included, it should begin searching the array from the value of the third argument (startingIndex).': function() {
    var myArray = [1, 2];
    var result = includes(myArray, 1, 1);
    eq(result, false);
  },
  'If startingIndex is negative, it should begin searching the array that many indexes from the end of the array.': function() {
    var myArray = [1, 2];
    var result = includes(myArray, 1, -1);
    eq(result, false);
  },
  'It should return a boolean value.': function() {
    var result = includes([1], 1);
    var type = (typeof result);
    eq(type, 'boolean');
  },
  'If the calculated value of arr.length + startingIndex is less than 0, it should search entire array.': function() {
    var myArray = [1, 2];
    var result = includes(myArray, 1, -3);
    eq(result, true);
  },
  'If startingIndex is greater than or equal to array.length, it should return false.': function() {
    var myArray = [1];
    var result = includes(myArray, 1, 3);
    eq(result, false);
  }




});
</script>