传递刚刚创建的参数

Question

我正在创建一个 NodeJS/Express 侦听器，并在创建我的 connectListener 时创建输入：

app.get('/server/:args', function(req, res) {
   res.sendFile(__dirname + '/index.html');
   // ... 
   var args = req.param("args");
   var client = net.connect({port : 50505}, connectListener(args, client));
});

然后我有我的 connectListener 功能：

function connectListener(args, client) {
    console.log("Connected to server.");
    console.log(args);
    client.write(args);
    // .... 
}

但是，我得到一个参数未定义的错误：

TypeError: Cannot read property 'write' of undefined
    at connectListener (C:\Users\ES\workspace_luna\WptHash\server-src\index.js:39:8)
    at C:\Users\ES\workspace_luna\WptHash\server-src\index.js:33:43
    at Layer.handle [as handle_request] (C:\Users\ES\workspace_luna\WptHash\server-src\node_modules\express\lib\router\layer.js:82:5)
    at next (C:\Users\ES\workspace_luna\WptHash\server-src\node_modules\express\lib\router\route.js:100:13)
    at Route.dispatch (C:\Users\ES\workspace_luna\WptHash\server-src\node_modules\express\lib\router\route.js:81:3)
    at Layer.handle [as handle_request] (C:\Users\ES\workspace_luna\WptHash\server-src\node_modules\express\lib\router\layer.js:82:5)
    at C:\Users\ES\workspace_luna\WptHash\server-src\node_modules\express\lib\router\index.js:235:24
    at param (C:\Users\ES\workspace_luna\WptHash\server-src\node_modules\express\lib\router\index.js:332:14)
    at param (C:\Users\ES\workspace_luna\WptHash\server-src\node_modules\express\lib\router\index.js:348:14)
    at Function.proto.process_params (C:\Users\ES\workspace_luna\WptHash\server-src\node_modules\express\lib\router\index.js:392:3)
Error: Can't set headers after they are sent.
    at SendStream.headersAlreadySent (C:\Users\ES\workspace_luna\WptHash\server-src\node_modules\express\node_modules\send\index.js:313:13)
    at SendStream.send (C:\Users\ES\workspace_luna\WptHash\server-src\node_modules\express\node_modules\send\index.js:494:17)
    at onstat (C:\Users\ES\workspace_luna\WptHash\server-src\node_modules\express\node_modules\send\index.js:585:10)
    at FSReqWrap.oncomplete (fs.js:99:15)

那么，我该如何正确创建 client 变量，以便它可以在下面的函数中使用？我制作函数 connectListener 这样而不是内联的原因是我计划跨更多端口复制客户端以处理同时连接，所以我不想重复使用代码，也不想使用全局客户端集 variables/array（虽然我想我可以...）

Answer 1

看起来问题是您正在调用 connectListener，您应该将其设置为在连接事件上调用的函数：

var client = net.connect({port : 50505}, connectListener);

如果您想使用特定的参数写入特定的客户端，您可以通过在 connectListener 函数中定义响应来实现：

app.get('/server/:args', function (req, res) {
    var client, args;

    res.sendFile(__dirname + '/index.html');
    // ... 

   function connectListener () {
       console.log("Connected to server.");
       console.log(args);
       client.write(args);
       // .... 
   }

   args = req.param("args");
   client = net.connect({port : 50505}, connectListener);
});

传递刚刚创建的参数

Passing arguments that are just getting created

javascript

function

anonymous-function

node.js

express