You'd think so, but web browsers are downright lobotomizing the ability for local HTML files to run any meaningful javascript code. Want to run a JS file from the same directory? CORS ERROR!!!!
Hence 200MB applications that are complete copies of the Chromium browser to run under 1MB of actual web code.
Isn't that the price of a relatively well sandboxed experience by browsers?
I've experienced the same limits building small tools for myself and friends that I wanted to contain in a single HTML file without external dependencies... but I understand why the same project without these restrictions could easily become malware, and ones that could be easily propagated.
[dead]
couldn't you just embed the js directly into the html file though? that would sidestep the CORS error. and since most of the people using a program like this are likely to be using AI to generate their ( likely throwaway ) applets anyway, readability and maintainability for the source doesn't matter as much as it would with human authors so having a separate js file doesn't bring that many advantages anyway.