Can't find socket.io.js [duplicate]

Answer 1

I know this seems obvious, but did you install Socket.IO on your server? Then you'll get a local copy of the file at '/socket.io/socket.io.js'.

npm install socket.io

Answer 2

Your Socket.IO server will handle serving the correct version of the Socket.IO client library; you should not be using one from elsewhere on the Internet. From the top example on the Socket.IO website:

<script src="/socket.io/socket.io.js"></script>

This works because you wrap your HTTP server in Socket.IO (see the example at How To Use) and it intercepts requests for /socket.io/socket.io.js and sends the appropriate response automatically.