title: Socket.io can't find localhost
body: <p>I was following <a href="https://www.youtube.com/watch?v=rxzOqP9YwmM" rel="nofollow noreferrer">this basic tutorial</a>, when I quickly found out that socket.io doesn't seem to detect my index.html and localhost gives error message 404. So maybe I had mistyped something, thus I copied <a href="https://github.com/WebDevSimplified/Realtime-Simple-Chat-App" rel="nofollow noreferrer">the files</a> from the tutorial, but the same issue persists. What am I missing?</p>