javascript - A form's "action" and "onsubmit": Which executes first?

Question

I'm trying to debug a webpage and I see a form element whose opening is

<form name="aspnetForm" method="post" action="default.aspx" onsubmit="javascript:return WebForm_OnSubmit();" id="aspnetForm">

Having only a base knowledge of web forms, I'm wondering what the order of execution is for the action and onsubmit.

Answer 1

If action was resolved first, then the browser would leave the page, the JS execution environment would go away, and there would be nowhere to run the JS in onsubmit, so it isn't.

Event handlers run before default actions. They can cancel default actions.