javascript - 如何解决node js中的ReferenceError(var未定义)

Question

我是 javascript 新手，我可能会问一些简单的问题。我正在尝试使用SockJS、nodeJs和nodeJs的ssh2模块开发一个项目。

我正在尝试使用 SockJS 库的客户端代码(websockets)从 Chrome 向 NodeJS 服务器发送消息，然后通过 ssh2 模块从 NodeJs 向我的树莓派发送消息。问题如下:

var http = require('http');
var sockjs = require('sockjs');
var Connection = require('ssh2');

var c = new Connection();
var sockserver = sockjs.createServer();


var server = http.createServer();
sockserver.installHandlers(server, {prefix:'/socksvr'});
server.listen(9999, '0.0.0.0');

sockserver.on('connection', function(conn) {

    c.connect({
        // Parameters to connect
    });

    //Here goes some code to check that the connection was successful

    conn.on('data', function(message) { 
    //this is when Node receives data from client socket

        //print somethings
        c.shell(onShell); // This is to send command from node to Raspberry Pi

    });

    //Here goes the problem 

    var onShell = function(err, stream) { 
        if (err != null) {
            console.log('error: ' + err);
        }

        stream.on('data', function(data, extended) {
            if (extended === 'stderr'){
                console.log('STDERR: '+data);
                conn.write(data);
            }else{
                if(data != ''){
                    console.log(':' + data);
                    conn.write(':' + data);
                }
            };        
        });

        stream.write(message);

    }

}); 

<小时/>

\server.js:62
stream.write(message);
             ^
ReferenceError: message is not defined
at onShell (C:\Documents and Settings\...\server.js:62:18)
at C:\Documents and Settings\...\node_modules\ssh2\lib\Channel.js:277:5
at Parser.<anonymous> (C:\Documents and Settings\...\node_modules\ssh2\l
ib\Channel.js:123:30)
at Parser.EventEmitter.emit (events.js:92:17)
at Parser.parsePacket (C:\Documents and Settings\...\node_modules\ssh2\l
ib\Parser.js:594:12)
at Parser.execute (C:\Documents and Settings\...\node_modules\ssh2\lib\P
arser.js:238:14)
at Socket.<anonymous> (C:\Documents and Settings\...\node_modules\ssh2\l
ib\Connection.js:488:18)
at Socket.EventEmitter.emit (events.js:95:17)
at Socket.<anonymous> (_stream_readable.js:746:14)
at Socket.EventEmitter.emit (events.js:92:17)

我知道在该函数中使用 message var 可能行不通，但我一直无法找到解决方案。我可能缺乏一些关于函数的知识。任何帮助表示赞赏。谢谢。

Answer 1

您的消息变量仅存在于 conn.on('data', 函数的范围内。您必须在 sockserver.on('connection' 或上面的范围内声明消息，以便它在两个函数中都可见.