How to implement EventSource on Codeignigter app?

I'm not very confident I understand the question. If you're asking how you get the form inputs at the controller - that is not changed from your original post.

PHP Code:

$date = trim(htmlspecialchars($this->input->post('date'))); 


Thanks for the reply! I should have been more specific in my response,
Yes, it seems like fetch will only send the form data in a format like above, with the weird "WebKitFormBoundary" stuff. I tried your trim solution, but it returned an empty string.

EDIT: I figure it out. The header was causing problems lol!