Javascript: Dialog Boxes

Here is a normal button that does nothing:

This code made the button:
<form method="POST">
<input type=reset value="Button">
</form>
If you want the button to show a dialog box after being clicked, edit the code to this:
<form method="POST">
<input type=reset value="Alert" OnClick="alert( This is an alert! )">
</form>

That results in: