sharepoint override form submission

Question

Is it possible to override a NewForm.aspx form submission in a sharepoint list? Without making changes to the NewForm.aspx page itself?

I would like something like the event handlers, where i can capture when an item is being added (ItemAdding) and perform some logic and set the properties.cancel = true, and .errormessage = "message" to let it fail on inserting. The problem with this is that the user cannot retain their data they inputted when going back to the form.

Answer 1

No, I don't believe there is a way to do what you want without "making changes" to NewForm.aspx page itself. You have already ruled out the method of use JavaScript and/or SharePoint ListEventHandler.