Solspace Freeform plugin: AJAX without jQuery – how? I am trying to post data using AJAX.

The docs describes a method here. But that is mainly for jQuery.

I have also looked at this url, which also uses jQuery.

But from what I understand, the "action" parameter in &lt;input type="hidden" name="action" value="freeform/api/form"&gt;is where the data is sent. But if I send data to that URL, I get a 404.

How do I properly submit a form using AJAX?
From the action you are currently posting to a controller see here 

The example shows that in your case it would be looking for a plugin called "Freeform" with a controller named "api" and then within that controller there would need to be a "form" action.  If this isn't there then the page will return a 404 or error as it cannot find the route.

You may be able to create the same thing without using jQuery with something like this method