How include Html file into another html file?

I have built a book marking app and also I have built a scrolling progress bar using Java Script, HTML, CSS. How do include both of these files together so that the scrolling progress bar will work inside my book marking app. Please help.
link to the code for bookmarking app -
link to the code for progress bar -

Hey @LP18Aug0041,

Please check, I have just pasted the essential logic into the bookmarking app.

Thank you for your help. But is there a way just to include that other file onto the main app file and not hard code into the main app file?

Using node js use HBS for it.
PHP use codeigniter for it
Django to templating
Check here , This site used html page inside it LINK

great stuff thanks for sharing