Adding JavaScript to the End Message in order to track clicks on external links

Dear community, 

I found a solution how to track clicks on external link when it is included in a question (e.g. here  https://community.qualtrics.com/custom-code-12/where-can-i-find-whether-participants-clicked-on-a-link-or-not-13806). 

However, I would like to track clicks when the external link is included in the end message.

How can I include the following JavaScript to the end message?

 

Qualtrics.SurveyEngine.addOnload(function() {

              jQuery('#extLink').click(function(event) {

                            Qualtrics.SurveyEngine.setEmbeddedData("clicked", "1");

                            jQuery("#NextButton").click();

              });

});

Will adding Embedded Data: clicked = 0, in the Survey Flow, before the end message containing the external link work? 

Thank you in advance for your helpful comments!

Best, 
Kor