Local JavaScript files often don’t work well in browsers these days.
Instead of opening the index.html page directly, you can serve it from a local webserver. For example: try opening a terminal for the directory that holds your index.html page, running python -m SimpleHTTPServer, and then visiting http://localhost:8000.
If its still giving you trouble, tell us a bit more about your OS — or where you’re trying to host your notebook, and perhaps we can further assist…