app.set('port',port)'TypeError:undefined不是函数'.初学者,需要创意

Question

我是业余学习用node.js构建的.我一直在按照教程创建我的第一个node.js应用程序.它工作得很好,直到我进入'npm start'.日志是:

C:\node\nodeteest3\bin\www:16
TypeError: undefined is not a function
    at Object.<anonymous> M+<C;\node\nodetest3\bin\www:16:5
    at Module_compile (module.js:460:26)
    at Object.Module._extensions..js (module.js:478:10)
    at Module.load (module.js:355:32)
    at Function.Module._load (module.js:310:12)
    at Function.module.runMain (module.js:501:10)
    at startup(node.js:129:16)
    at node.js:814:3

然后它输出大约20行,以"npm ERR!"+文件路径开头,我认为没有必要,因为错误似乎在bin文件中.这个代码是

#!/usr/bin/env node
/**
* Module dependencies.
*/

var app = require('../app');
var debug = require('debug')('nodetest3:server');
var http = require('http');

/**
* Get port from environment and store in Express.
 */

var port = normalizePort(process.env.PORT || '3000');

这是错误指向的地方:

[app.set('port', port);]

------- ^错误指针在's' - 如此清楚关于set ------------

app.set('port', port);
 /**
 * Create HTTP server.
 */

var server = http.createServer(app);

 /**
 * Listen on provided port, on all network interfaces.
 */

server.listen(port);
server.on('error', onError);
server.on('listening', onListening);

 /**
 * Normalize a port into a number, string, or false.
 */

function normalizePort(val) {
    var port = parseInt(val, 10);

  if (isNaN(port)) {
    // named pipe
    return val;
  }

  if (port >= 0) {
    // port number
    return port;
   }

   return false;
}

/**
* Event listener for HTTP server "error" event.
*/

function onError(error) {
  if (error.syscall !== 'listen') {
    throw error;
  }

  var bind = typeof port === 'string'
    ? 'Pipe ' + port
    : 'Port ' + port;

  // handle specific listen errors with friendly messages
  switch (error.code) {
    case 'EACCES':
      console.error(bind + ' requires elevated privileges');
      process.exit(1);
      break;
    case 'EADDRINUSE':
      console.error(bind + ' is already in use');
      process.exit(1);
      break;
    default:
      throw error;
  }
}

/**
 * Event listener for HTTP server "listening" event.
 */

function onListening() {
  var addr = server.address();
  var bind = typeof addr === 'string'
    ? 'pipe ' + addr
    : 'port ' + addr.port;
  debug('Listening on ' + bind);
}

Like I said in the beginning, I'm a complete beginner with command-line/github, but I'm already in love with it. I try to practice it every night after I finish my homework, and am getting really frustrated about getting stuck because I haven't been able to move forward for four days now. Also, I'm running this on node.js and the OS is Windows 8. Anything helps!  Let me know if you want me to post any of the other code; I omitted so as to not add more than necessary.

 "../app (app.js file) JUST ADDED"***************************
../app file:
    [ App.js   ]
 var express = require('express');
 var path = require('path');
 var favicon = require('serve-favicon');
 var logger = require('morgan');
 var cookieParser = require('cookie-parser');
 var bodyParser = require('body-parser'); 

var routes = require('./routes/index');
var users = require('./routes/users');
var app = express();

///  catch 404 and forwarding to error handler
app.use(function(req, res, next) {
    var err = new Error('Not Found');
    err.status = 404;
    next(err);
});
var app = express();
// error handlers

// development error handler
// will print stacktrace
if (app.get('env') === 'development') {
        app.use(function(err, req, res, next) {
        res.status(err.status || 500);
        res.render('error', {
            message: err.message,
            error: err
        });
    });
}


var app = express();


// view engine setup
app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'jade');

// uncomment after placing your favicon in /public
//app.use(favicon(__dirname + '/public/favicon.ico'));
app.use(logger('dev'));
app.use(bodyParser.json({estended: true}));
app.use(bodyParser.urlencoded({extended: true}));
app.use(cookieParser({extended:true}));
app.use(express.static(path.join(__dirname, 'public')));

app.use('/', routes);
app.use('/users', users);





//  production error handler
// no stacktraces leaked to user
app.use(function(err, req, res, next) {
    res.status(err.status || 500);
    res.render('error', {
        message: err.message,
        error: {}
    });
});

Answer 1

您没有在app.js文件中导出任何内容.在app.js文件末尾,包括以下行.

module.exports = app;

看看你的问题是否消失了.

还有一个补充:你有var app = express();两次app.js.

Answer 2

您没有声明文件set内调用的任何函数app.js。创建该函数并将其导出，如下所示：

exports.set = function(...) { ... };

如果这app是快递，app请指定这样的端口：

var express = require('express'),
    http = require('http');

var app = express();

http.createServer(app).listen(port);

代替

app.set('port', port);
 /**
 * Create HTTP server.
 */

var server = http.createServer(app);

这是因为端口是 http 服务器的属性，而不是 Express 应用程序的属性

您还可以使用

var express = require('express'),
    app = express();

app.listen(port);