Question

我是node.js的新手我试图实现example。当我运行node app.js时，我收到地图错误，如下所示：

错误

oneadmin@openflow1:~/Desktop/test-projects/nodejs/example$ node app.js
   info  - socket.io started
/home/oneadmin/Desktop/test-projects/nodejs/example/app.js:17
    io.sockets.emit('tweets', obj.results.map(function (v) { return v.text; })
                                         ^
TypeError: Cannot read property 'map' of undefined
    at Request._callback (/home/oneadmin/Desktop/test-projects/nodejs/example/app.js:17:42)
    at Request.self.callback (/home/oneadmin/Desktop/test-projects/nodejs/example/node_modules/request/main.js:122:22)
    at Request.EventEmitter.emit (events.js:107:17)
    at Request.<anonymous> (/home/oneadmin/Desktop/test-projects/nodejs/example/node_modules/request/main.js:655:16)
    at Request.EventEmitter.emit (events.js:126:20)
    at IncomingMessage.<anonymous> (/home/oneadmin/Desktop/test-projects/nodejs/example/node_modules/request/main.js:617:14)
    at IncomingMessage.EventEmitter.emit (events.js:126:20)
    at _stream_readable.js:895:16
    at process._tickCallback (node.js:343:11)

app.js

var sio = require('socket.io')
  , http = require('http')
  , index = require('fs').readFileSync(__dirname + '/index.html')
  , request = require('request')

var app = http.createServer(function (req, res) {
    res.writeHead(200, { 'Content-Type': 'text/html' });
    res.end(index);
  })
  , io = sio.listen(app);

setInterval(function () {
  request({
    url: 'http://search.twitter.com/search.json?q=today'
  }, function (err, res, data) {
    var obj = JSON.parse(data);
    io.sockets.emit('tweets', obj.results.map(function (v) { return v.text; }));
  });
}, 2000);

io.sockets.on('connection', function (socket) {
  socket.broadcast.emit('someone connected');

  socket.on('some event', function () {
    console.log('I got an event');
  });
});

app.listen(3000);

的index.html

<!doctype html>
<html>
  <head>
    <script src="/socket.io/socket.io.js"></script>
    <script src="http://ajax.googleapis.com/ajax/libs/jquery/1.6.2/jquery.min.js"></script>

    <script>
      var socket = io.connect();

      $(function () {
        socket.on('tweets', function (tweets) {
          $.each(tweets, function (i, tweet) {
            $('#tweets').prepend($('<li>').text(tweet));
          });
        });

        socket.on('someone connected', function () {
          $('body').prepend('<p>Someone just connected!</p>');
        });

        socket.emit('some event');
      });
    </script>
  </head>
  <body>
    <h1>Tweets</h1>
    <ul id="tweets"></ul>
  </body>
</html>

任何人都帮我删除此错误提前谢谢！

Answer 1

您可能需要在使用之前检查返回的值：

    if (obj && obj.results) {
        io.sockets.emit('tweets', obj.results.map(function (v) { 
             return v.text; 
        }));
    }

但真正的问题是：为什么obj.results未定义？我检查了网址http://search.twitter.com/search.json?q=today并返回了此信息：

{ 错误：[ { 消息：＆＃34; Twitter REST API v1不再处于活动状态。请迁移到API v1.1。 https://dev.twitter.com/docs/api/1.1/overview。＆＃34 ;, 代码：64 } ] }

这就是为什么obj.results未定义的原因。

TypeError：无法读取属性＆＃39; map＆＃39;未定义的

1 个答案: