Github is a online code repository. For anyone who writes code - text files full of odd symbols - git is probably an everyday thing. Git is designed to handle text files. Unfortunately for us, FileMaker databases are binary data, so we can't take easily take advantage of the version control system that makes Git such an amazing tool for coders working in other languages.
Though we may not use Git for version control we can still use Github as a treasure trove of great things that expand our use of FileMaker. If you want to see what other filemaker developers are doing on github, you can search for "filemaker".
Javascript is now a first class citizen inside Web Viewers and quickly becoming an important tool. Github has oodles of amazing javascript repositories that can be brought into FileMaker. You can search for "filemaker javascript" to find javaScript projects that relate to FileMaker. You may notice the number of repositories is quite small but that doesn't reflect the full story.
When you search for javaScript by itself there are way too many javaScript repos to browse through (over a million) so I suggest that you narrow your search to things that you might be interested in implementing : like gantt charts for project management, or an image gallery, or data tables with really cool controls, or data visualisation tools.
You'll find amazing stuff on Github but you may not have the coding experience to implement those repositories yourself. Fortunately, there is help at hand. Soliant has been building tools for this purpose and making them available at https://carafe.fm. The website has good documentation to get you started. And, of course, you can find the Carafe.fm project on Github.