title: Check is changed value in text box using class
body: <p>I have text boxes with .numeric class. I want check value had change or not after the edit that value. </p>
  
  <p>I found this code after google. </p>
  
  <pre><code>var previousValue = $("#elm").val();
  $("#elm").keyup(function(e) {
      var currentValue = $(this).val();
      if(currentValue != previousValue) {
           previousValue = currentValue;
           alert("Value changed!");
      }
  });
  </code></pre>
  
  <p>But this code will work for only one text field (with id <code>#elm</code>). What should I do if I want to make it work for multiple fields (sharing the class <code>numeric</code>) ?</p>