Can I use my HTML form to perform multiple actions?
At the moment I can post the filled form to the destination but cant navigate the user to another page using HTML specifically. Is there any method in HTML to do this?
Any suggestions?
Things are easy if you control the server and/or are on the same domain, then you can do a server side redirect. But since you are using salesforce surely you don't control that. Nevertheless, double check their documentation for a redirect option you can put in the form.
If that fails, one thing I'd try is to submit it to an iframe: add <iframe name="foo" id="foo"></iframe> somewhere to your html (you can hide it too if you want) and add target="foo" to your form. Then, also add an onsubmit javascript handler to the form that redirects after a delay to allow the form to be processed. The timing of the delay is likely to be a source of bugs btw, checking for errors in the submitted form can't be easily done across domains, you'd be guessing. Maybe an onload handler on the iframe can do the redirect though, I'm not sure, but worth a try.
This isn't guaranteed to work either, some sites don't like being in iframes. If that fails, you might try setting target="_BLANK" to submit the form to a popup window then redirect your main window using javascript or something. This will require you to give an instruction to the user to close the window.
Lastly, if you can submit the data via a server side API call to salesforce, that would be good too because then the plain redirect option is back under your control.