ReferenceError：在NodeJS中未定义io

Question

I have a NodeJS project and need one of the variable defined in my app.js file in another file, this is possible?

My code

app.js

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

otherFile.js

var models  = require('../models');
var express = require('express');
var path    = require('path');
var fs      = require("fs"); //To-Delete
var recursive = require('recursive-readdir');
var router  = express.Router();

var app = require ('../app.js');

// creating a new websocket to keep the content updated without any AJAX request
app.io.sockets.on('connection', function(socket) {

  fs.watchFile(__dirname + '../README.md', function(curr, prev) {
    // on file change we can read the new xml
    fs.readFile(__dirname + '../README.md', function(err, data) {
      if (err) throw err;
      // parsing the new xml data and converting them into json file
      // var json = parser.toJson(data);
      // send the new data to the client
      socket.volatile.emit('notification', {message: 'el archivo cambio'});
    });
  });

});

the error that I get in this case is TypeError: Cannot read property 'sockets' of undefined

Blockquote

Answer 1

When you do:

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

You just create a local variable, that is visible only within the scope of that file.

If you want to get access to it from another file using app.io after just importing app , you need to:

• add io as a property of your app:

   app.io = io; 

or simply combine both:

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

• of course, export the app itself

Answer 2

from the socket.io docs this should work:

var app = require('express')();
var server = require('http').Server(app);
var io = require('socket.io')(server);
io.sockets.on('connection', function(socket) {
    // ... your code
});