For some reason I have never needed to use the defautlValue property up until today. I was pleased to find javascript can access the original input value so tracking changes in a form is a bit easier. However, the defaultValue only works as expected for “text”, “file”, and “password” fields.
http://www.w3.org/TR/DOM-Level-2-HTML/html.html#ID-6043025
A workaround is to use type=”text” and just have a style=”display:none;” to act like a hidden field.