The defaultValue property is not initialized for the WebDatePicker control. The control is initialized from the code-behind in the page_load event but the element.defaultValue is empty.

We have a generic javascript "form is dirty" implementation that checks if anything has changed in the browser.

This check always return true in the javascript function.

if (type == "hidden" || type == "password" || type == "text" || type == "textarea" || type == "file") {
            if (element.value != element.defaultValue) {
                return true;
            }       }

Is there a way to set the defaultValue to the value initalized in the code-behind?

Here is my HTML for the control - 

<ig:WebDatePicker ID="StartDateWebDatePicker" runat="server">
</ig:WebDatePicker>