Is there any offline programming app i could use to learn?

Answer 1

try anwriter a good editor app for html, css, JavaScript includes built-in console.log, tabs for multiple text files, syntax, highlighting, auto complete, smooth, modern material design app, etc.
https://play.google.com/store/apps/details?id=com.ansm.anwriter&hl=en
anWriter free HTML editor - Android Apps on Google Play

quoda is a little old crashes sometimes but good. check if it's okay for you, includes tabs for multiple files , auto complete, shortcuts, etc open in web browser, etc.
https://play.google.com/store/apps/developer?id=Quoda&hl=en
Quoda - Android Apps on Google Play

there is 920 text editor completely free but without auto completion
https://play.google.com/store/apps/details?id=com.jecelyin.editor.v2&hl=en
920 Text Editor - Android Apps on Google Play

//online for most features but works offline for text editing
codeanywhere is a powerful cloud based text editor supports nearly all languages you will ever need, supports Github, bitbucket, Ubuntu VM, auto complete, syntax highlighting, code beautiful, complete customisation, Linux virtual machine ready for development, so on.
https://play.google.com/store/apps/developer?id=Codeanywhere,+Inc.
Codeanywhere, Inc. - Android Apps on Google Play

Answer 2

https://code.sololearn.com/WY1YrUIkSl5p/?ref=app