plugins - Wordpress - Adding javascript to head on successful submission of contact form 7 -

I am trying to write a plugin that successfully gives the user the successful output of HTML or JavaScript in the main part of my page Allows to offer a contact form 7. I tried to use wpcf7_before_send_mail, but I have not had any success.

Thank you in advance for any help

(Official doctor shows redirection)

  on_sent_ok: "customfunction ();"  

and then whatever you want in that function

  & lt; Script & gt; Function custom function () {} & lt; / Script & gt;