Question

io.sockets.emit工作正常并将消息发送到所有连接的套接字，但socket.emit不起作用且socket未定义。

有什么想法吗？

var app = require('express')();
  var http = require('http').Server(app);
  var io = require('socket.io')(http);
  var net = require('net');
  var express = require('express');
  var sqlite3 = require('sqlite3').verbose();
  var db = new sqlite3.Database('test-db.db');


  var tools = require('./public/js/tools.js');
  var app_tools = require('./public/js/app.js');

  db.serialize(function() {
          db.run("CREATE TABLE if not exists names (info TEXT)");
  });

  app.use(express.static(__dirname + '/public'));

  app.get('/', function(req, res){
    res.sendFile(__dirname + '/index.html');
  });

  io.on('connection', function(socket){
          socket.on('chat message', function(msg){
      console.log('message from geomon-ui: ' + msg);
      if(msg.indexOf("add") >= 0)
      {
          console.log("adding to database table");
        var words = msg.split(' ');
        console.log("name to add = " + words[1]);
        var insertString = "INSERT into names  (info) VALUES ('" +
  words[1] + "')";
          db.run(insertString);
          db.each("SELECT rowid AS id, info FROM names", function(err, row) {
          console.log(row.id + ": " + row.info);
          });
      }
      else if(msg.indexOf("delete") >= 0)
      {
        console.log("deleting from database table");
        var words = msg.split(' ');
        console.log("name to delete = " + words[1]);
        var deleteString = "DELETE from names WHERE (info) = '" + words[1] + "'";
        console.log(deleteString);
        db.run(deleteString);
        db.each("SELECT rowid AS id, info FROM names", function(err, row) {
          console.log(row.id + ": " + row.info);
        });
      }
      else if(msg == "print")
      {
          db.each("SELECT rowid AS id, info FROM names", function(err, row) {
          console.log(row.id + ": " + row.info);
          });
      }
      else if(msg == "status off")
      {
        console.log(socket);
        console.log(io.sockets);

          socket.emit("colorChange", { status: 'off' });
      }
      else if(msg == "status on")
      {
       io.sockets.emit("colorChange", { status: 'on' });
      }
      else if(msg == "hello")
      {
          tools.hello();
      }
      else if(msg == "send")
      {
        var HOST = '10.1.1.200';
        var WRITEPORT = 8889;
        var socket = net.createConnection(WRITEPORT, HOST);
        socket.write('status=Encrypt input=Kyle');

        var READPORT  = 8888;
        var tcpServer = net.createServer(function(sock) {
            console.log('CONNECTED: ' + sock.remoteAddress +':'+ sock.remotePort);
            sock.on('data', function(data) {
                console.log('DATA ' + sock.remoteAddress + ': ' + data);
                var cont = data.toString();
                io.sockets.emit("printMessage", { content: cont });
            });

            sock.on('uncaughtException', function(err) {
              console.log(err);
            });

            sock.on('error', function() {
              console.log("error");
            });

            sock.on('end', function() {
              tcpServer.close();
            });


        }).listen(READPORT, HOST);
      }
    });
  });

  http.listen(3000, function(){
    console.log('listening on localhost:3000');
  });

编辑：这是我正在运行的确切代码。如果你运行它，然后转到输入文本框并输入“status off”，你可以看到套接字未定义。

Answer 1

问题在于这一行：

var socket = net.createConnection(WRITEPORT, HOST);

在Javascript中，变量是"hoisted"到其范围的“顶部”。

在你的情况下，你正在做类似的事情：

socket.on('chat message', function(msg) {
  var socket; // this will clobber the previous 'socket' variable!

  if (msg == "status off") {
    // socket _will_ be undefined here!
  } ...
  else if (msg == "send") {
    socket = net.createConnect(...);
  }
});

if块不会启动新范围，因此if块中的任何变量声明都会被提升。

最快的解决方案：不要将变量命名为socket，而是将其称为其他变量。

定义了io.sockets，但socket不定义

1 个答案: