teunvink on "[Plugin: Contact Form 7] using form data after redirect"

Using the hints in https://wordpress.org/support/topic/adding-custom-variables-to-on_sent_ok-redirect-url?replies=2 I fixed it this way:

I added an 'id:name' tag to the form field, and in the additional settings I added:

on_sent_ok: "var name = document.getElementById('name').value; redir='http://example.com/index.php?name='+encodeURIComponent(name); window.location = redir;"