title: Angular input value not changed. i.e oldValue == newValue
body: <p>Angular adds 'ng-dirty' class to input field when the input field is modified irrespective of whether <code>newValue==oldValue</code> or not.</p>
  
  <p>i.e. if the input value is 'manohar', and i delete 'r' and add it back. Even though the value is 'manohar'( original value), the 'ng-dirty' class still exists.</p>
  
  <p>Is there a way to check whether the input value is modified or not(<code>newValue != oldValue</code>)?</p>
  
  <p>Thanks in advance.</p>