Detecting data changes in forms using jQuery

Quick (but very dirty) solution

This is quick, but it won't take care of ctrl+z or cmd+z and it will give you a false positive when pressing shift, ctrl or the tab key:

$('#my-form').on('change keyup paste', ':input', function(e) {
    // The form has been changed. Your code here.
});

Test it with this fiddle.

---

Quick (less dirty) solution

This will prevent false positives for shift, ctrl or the tab key, but it won't handle ctrl+z or cmd+z:

$('#my-form').on('change keyup paste', ':input', function(e) {

  var keycode = e.which;

  if (e.type === 'paste' || e.type === 'change' || (
      (keycode === 46 || keycode === 8) || // delete & backspace
      (keycode > 47 && keycode < 58) || // number keys
      keycode == 32 || keycode == 13 || // spacebar & return key(s) (if you want to allow carriage returns)
      (keycode > 64 && keycode < 91) || // letter keys
      (keycode > 95 && keycode < 112) || // numpad keys
      (keycode > 185 && keycode < 193) || // ;=,-./` (in order)
      (keycode > 218 && keycode < 223))) { // [\]' (in order))

    // The form has been changed. Your code here.

  }

});

Test it with this fiddle.

---

A complete solution

If you want to handle all the cases, you should use:

// init the form when the document is ready or when the form is populated after an ajax call
$(document).ready(function() {
  $('#my-form').find(':input').each(function(index, value) {
    $(this).data('val', $(this).val());
  });
})

$('#my-form').on('change paste', ':input', function(e) {
  $(this).data('val', $(this).val());
  // The form has been changed. Your code here.
});

$('#my-form').on('keyup', ':input', function(e) {
  if ($(this).val() != $(this).data('val')) {
    $(this).data('val', $(this).val());
    // The form has been changed. Your code here. 
  }
});

Test it with this fiddle.

You could bind the Change event for all inputs and flag a variable as true. Like this.

var somethingChanged = false;
$(document).ready(function() { 
   $('input').change(function() { 
        somethingChanged = true; 
   }); 
});

But, keep in mind that if the user changes something, then changes back to the original values, it will still be flagged as changed.

UPDATE: For a specific div or fieldset. Just use the id for the given fieldset or div. Example:

var somethingChanged = false;
$(document).ready(function() { 
   $('#myDiv input').change(function() { 
        somethingChanged = true; 
   }); 
});