Can I store some data in a file created by JavaScript in web page and retrieve data anytime from JavaScript

Answer 1

No, JavaScript codes are not allowed to create and read any files.
Use localStorage.setItem localStorage.getItem to store/read all the persistent data of a local device.

Answer 2

Use localStorage or cookies. But localStorage will not work in the Soloearn App due to security restrictions, you may test it in webbrowser. If cookies work here i dont know, havent tested it myself.

Answer 3

localStorage is a good option it.