As far as I have seen, there is no explanation as to where we are to locate the client side script for socket.io if node.js is not used as the web
socket.io
node.js
socket.io.js is what you're going to put into your client-side html. Something like:
my script is located:
/usr/local/lib/node_modules/socket.io/node_modules/socket.io-client/dist/socket.io.js
copy that file to where you want your server to serve it.