Improvements for JS code

[vietthedev]

Hi @mrrfv, I specialise in JS and I think I can help improve various aspects of the code after going through the codebase. These are what I can think of so far:

• Modularise common code
• Optimise the domain processing code
• Remove axios and use fetch to reduce dependencies
• Only install dotenv in local environment

And maybe porting the list download code to JS because I/O operations is node's strength anyway. It also makes it more portable.