Adding Code Snippet from Gist to Markdown

How can we insert a code snippet from Gist to Markdown?

I guess this is the common problem for a lot of new users that jump to the website static types especially related to Github or website generator like Jekyll or the others. So, let’s do this thing!

This is the pattern how to insert Gist (copy directly to the markdown file):

<script src="https://gist.github.com/username/ID.js?file=filename.extension"></script>

This is the example result: