ES6 modules in local files - The server responded with a non-JavaScript MIME type

Question

I get this error:

Failed to load module script: The server responded with a non-JavaScript MIME type of \"\". Strict MIME type checking is enforced fo

Answer 1

ES6 module files are loaded using the standard Same-Origin policy restrictions that browsers enforce and have many other security restrictions in place, while JavaScript "script" files have much more lax security to avoid breaking existing websites as better security standards have been added to browsers over time. You are hitting one of them, which is that files must be sent with the correct MIME type.

file:// URLs are not normal HTTP requests, and as such they have different rules around requests. There's also pretty much no rules for what MIME type should be sent. If you want to use ES6 modules then you need to be running a real HTTP server locally to serve your files.