How to add Facebook Like button to javascript plugin

I have a javascript quiz plugin (created by a third party) which works well but has a Facebook Share button which is obsolete and no longer works.

I want to add a Facebook Like button to the final page of the quiz and ideally I’d like it to display the user’s score when it appears as an update on their newsfeed/timeline in Facebook.

Any tips on how I can do this? I have added Facebook Like buttons to websites in the past but I’m a javascript novice.

Hmm, without seeing the obsolete code or even knowing the plugin name it’s kinda hard to know what exactly you need. The best I can do is point you to this article which shows you how to make a post , if you show me some code I can probably help you out a little better.