I thought I would quickly share this.

I had downloaded a website which was just a stupid scam - Immediate Vortex  - and the downloaded website worked fine in my browser when I opened it locally, but never from a URL.

I could not find any references that were broken but finally realised that it was the mime types - the IIS server I had saved to did not have .download or . registered as application/javascript so it would just return an error redirect. I shoudl have checked the browser console earlier.

All I did was add these mime types to the server and the website started working again as normal.