(post deleted by author)
Eheh it happened the same to me few times ago
If you’re testing no-network stuff you can just open the file ( that behaviour with jQuery make me think there are other kind of problems^^).
If you do not want to setup webpack ( for the dev server ) you can use a simpler bundler (parcel is the first i can think of), otherwise there are a lot of packages that will serve your html; for example, in the same folder of your html you can write
npx serve . and you are good to go
If you use Microsofts Visual Stuidio Code, there is an extension calledd Live Server which will refresh your browser everytime your code changes.