While writing my blog posts for my readers I noticed that every time I use "<" or ">" signs to show JavaScript or HTML codes and snippets within my Blogger post editor in "Edit HTML" mode, it's not visible. This happens because Blogger post editor recognizes it as snippets that should be used with your blogger template.
So to show JavaScript or HTML codes within Blogger posts or comments, use "<" instead of "<" and ">" instead of ">" (without quotes).
Now if there are big codes then go to Plus2net.com and convert your codes.
This is the simplest method to show JavaScript and HTML codes within blog posts.