Multiple files and importing libraries

I have been working with Arduino and MicroPython for a while and just switched to Espruino and nodejs on ESP8266. I am able to upload a file and connect to wifi and do lots of stuff. But there's one thing I cannot figure out:

MicroPython had a file structure like below:

• boot.py
  
• main.py
  
• mylibrary.py
  
  

as the name suggests boot.py is executed on boot, and main.py is the main file where you want to create your main loop. I can create another library and import it from main.py. Arduino also has similar structure. How can I do this in Espruino? Can I upload multiple files? If so how?