Ordered set up to nth element

<html>
<head>
     <title>Ordered</title>
</head>
<body>
    <h1> Test Header </h1>

  <script>
    var p = 7,
            vector = [3, 5, 13, 26, 54, 22];

function isOrdered(array, elementNumber) {
     // Check if the array has enough elements
     if (array.length < elementNumber) {
          return[null, 'Array does not have '+elementNumber+((elementNumber == 1) ? ' element' : ' elements')];
     }

     // Initialize direction
     var direction = null,
                 segment = [],
                 currentComparition;

     // Loop up to the nth element
     for (var i = 0; i < elementNumber-1; i++) {
                // Compare elements
                if (array[i] < array[i+1]) {
                     currentComparition = 'lower';
                } else if (array[i] == array[i+1]) {
                     currentComparition = 'equal';
                } else if (array[i] > array[i+1]) {
                     currentComparition = 'bigger';
                }

             // Set the direction (if not set)
             if (!direction) {
                  if (currentComparition != 'equal') {
                     direction = currentComparition;
                  }
             }

             // Add the first compared element to the segment
             segment.push(array[i]);

             // Check if direction is kept
             if (direction) {
                  // Unordered
                  if (direction != currentComparition && currentComparition != 'equal') {
                     // Add last element
                     segment.push(array[i]);
                     return [false, segment];
                  }
             }
     }

     // Add last element
     segment.push(array[i]);
     // Return ordered result
     return [true, segment];
}

var result = isOrdered(vector, p);

if (result[0]) {
    document.write('Set is ordered: ' + result[1].join(', '));
} else {
  if (result[0] === null) {
     document.write(result[1]);
  } else {
    document.write('Set is not ordered');
  }
}
  </script>
</body>
</html>