That's all. Then I try to use socket.io with this line:

var io = require('socket.io').listen(app);

And it output an error:

Error: Cannot find module 'socket.io'

    at Function.Module._resolveFilename (module.js::)

    at Function.Module._load (module.js::)

    at Module.require (module.js::)

    at require (module.js::)

    at Object.<anonymous> (F:\nodejs\chat.js::)

    at Module._compile (module.js::)

    at Object.Module._extensions..js (module.js::)

    at Module.load (module.js::)

    at Function.Module._load (module.js::)

    at Function.Module.runMain (module.js::)

I've tried all suggested method like cleaning cache, reinstalling nodejs or changing socket.io module path. Unfortunately, all of those solutions didn't solve this problem.

This terrible error killed my whole day. I greatly appreciate any help.

解决方法：

Try to execute npm install socket.io in the folder where your node.js file is (where you require the module). npm creates a folder node_modules wherever you execute npm install socket.io and you probably didn't do this in the correct folder.

npm install supervisor -g did work because -g is the global flag and you can basically do that anywhere.