This page demonstrates how a visual clue can be given that a form
field has changed value. The inputs below get their default value from
the server ("field x content"). In the onload event of
the page, onblur event handlers are registered for the
controls, and in these events, the value of the controls is compared
to the value in the defaultValue property. The
className property of the control is set accordingly.
If another page is loaded from this test page (say, the validation
pages), and the back button is pressed, the form controls'
className property revert back to their original value.
Therefore, the page's onload event is also used to
immediately compare the control's content with the
defaultValue property.
There are many different ways to achieve the desired goal. In this
case, an approach was chosen that can easily be dropped-in into
existing forms. An alternative would be to set explicit event handlers
in HTML. Note that the code assumes inputs of type text; real-world
code would probably need to check for other controls, and for the
presence of onblur event handlers.
Note that this is work in progress, it's unfinished for anything but the text input fields!
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