ajax - Node.js 长轮询事件循环破坏了整个代码

Question

我对编程完全陌生，在开发网站的这个阶段，我需要设置一个简单的长轮询请求以从数据库获取最新消息，然后将它们显示给客户端。我昨天创建了一个消息系统，现在它保存了消息以及消息和用户之间所有需要的关系...

这是我所做的:

var express = require('express');
var router = express.Router();
var Conversation = require('../models/conversation');
var Promise = require('promise');

// Get Homepage
router.get('/', function(req, res){
	res.render('index');
});


var messages = [];
router.get('/inbox', function(req, res){
	var promise = new Promise(function (resolve, reject) {
		req.user.conversations.forEach(function(id){
			Conversation.getConversationById(id, function(err, conv){
				if (conv){
					messages.push(conv);
					if(messages.length == req.user.conversations.length){
						resolve(messages);
						messages = [];
					}
				} else {
					console.log(err);
				}
			});
		});
	}).then(function(object){
		res.render('inbox', {convers: object});
	}).catch(function(err){
		console.log(err);
	});
});

// Add new messages to messagesArray -> mesgArray to display them
var mesgArray = [];
var userIdFor = "";
router.post('/messages', function(req, res){
	var convId = req.body.conversationId;
	userIdFor = req.user.id;
	var promise = new Promise(function(resolve, reject){
		Conversation.getConversationById(convId, function(err, conver){
			if (err){
				console.log(err);
			} else {
				conver.messages.forEach(function(messa){
					mesgArray.push({msg: messa.msg, owner: messa.msgOwner, ownerName: messa.msgOwnerName});
					if(mesgArray.length == conver.messages.length){
						resolve(mesgArray);
					}
				});
			}
		});
	}).then(function(object){
		res.send({allMessages: object, userId: userIdFor});
		mesgArray = [];
		userIdFor = "";
	}).catch(function(err){
		console.log(err);
	});
});

// Save posted message to existent conversation
router.post('/saveMsg', function(req, res){
	var conversationId = req.body.conversationId;
	var messageToSave = req.body.message;
	console.log(messageToSave);
	console.log(conversationId);
	Conversation.getConversationById(conversationId, function(err, conversation){
		if (err){
			console.log(err);
		} else {
			Conversation.getConversationById(conversationId, function(err, conversation){
				if(err){
					console.log(err)
				} else {
					conversation.messages.push({
						msg: messageToSave,
						msgOwner: req.user.id,
						msgOwnerName: req.user.firstName
					});
					conversation.save(function(err){
						if(err){
							console.log(err);
						}
					})
				}
			});
		}
	});
});

module.exports = router;

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.2.3/jquery.min.js"></script>
<!-- REPLAY MESSAGE BOX -->
<div class="contact-form-container hidden-mode">
  <div class="row hide-contact text-right">
    <img src="/images/close.png">
  </div>
  <form>
    <div class="inbox-all-messages-container">
      <div class="row inbox-all-messages">
         <!-- Here will be all the messages -->
      </div>
      <div class="row text-center inbox-send-input">
        <div class="col-lg-11 col-md-11 col-sm-11">
          <textarea class="inbox-message-response-txt" placeholder="Type your message here"></textarea>
        </div>
        <div class="col-lg-1 col-md-1 col-sm-1 text-center inbox-message-send-btn">
          <p class="inbox-message-send-msg-btn">Send</p>
        </div>
      </div>
    </div>
  </form>
</div>
<script>
  $(document).ready(function(){

  var convId = "";
  $('.inbox-messager').on('click', function(){
    $('.inbox-all-messages').empty();
      var conversationId = this.getAttribute("data-conv-id");
      convId = conversationId;
      $.ajax({
        url: '/messages',
        method: 'POST',
        contentType: 'application/json',
        data: JSON.stringify({conversationId: conversationId}),
        success: function(response){
          response.allMessages.forEach(function(message){
            if(message.owner == response.userId){
              $('.inbox-all-messages').append(
                '<div class="row inbox-message-structure-meNot">'+
                  '<div class="row inbox-message-header">'+
                      '<div class="inbox-message-ava col-lg-1 col-md-1 col-sm-1">'+
                        '<img src="/images/avatar.jpg" class="inbox-message-header-ava-img">'+
                      '</div>'+
                      '<div class="inbox-message-header-senderName col-lg-3 col-md-3 col-sm-3">'+
                        '<p>' + message.ownerName + '</p>'+
                      '</div>'+
                      '<div class="col-lg-3 col-lg-offset-5 col-md-3 col-md-offset-5 col-sm-3 col-sm-offset-5 inbox-message-header-sentTime text-right">'+
                        '<p>24/05/2016</p>'+
                      '</div>'+
                  '</div>'+
                  '<div class="row inbox-message-body">'+
                    '<div class="col-lg-9 col-lg-offset-1 col-md-9 col-md-offset-1 col-sm-9 col-sm-offset-1 text-left">'+
                      '<p>' + message.msg + '</p>'+
                    '</div>'+
                  '</div>'+
                '</div>'
              );
              
            } else {
              $('.inbox-all-messages').append(
                '<div class="row inbox-message-structure-me">'+
                  '<div class="row inbox-message-header">'+
                      '<div class="inbox-message-ava col-lg-1 col-md-1 col-sm-1">'+
                        '<img src="/images/client.jpg" class="inbox-message-header-ava-img">'+
                      '</div>'+
                      '<div class="inbox-message-header-senderName col-lg-3 col-md-3 col-sm-3">'+
                        '<p>' + message.ownerName + '</p>'+
                      '</div>'+
                      '<div class="col-lg-3 col-lg-offset-5 col-md-3 col-md-offset-5 col-sm-3 col-sm-offset-5 inbox-message-header-sentTime text-right">'+
                        '<p>24/05/2016</p>'+
                      '</div>'+
                  '</div>'+
                  '<div class="row inbox-message-body">'+
                    '<div class="col-lg-9 col-lg-offset-1 col-md-9 col-md-offset-1 col-sm-9 col-sm-offset-1 text-left tester">'+
                      '<p>' + message.msg + '</p>'+
                    '</div>'+
                  '</div>'+
                '</div>'
              );
            }
          });
          $('.inbox-all-messages').append('<div id="bottom"></div>');
          $('.inbox-all-messages').scrollTo('#bottom', 100, "max");
        }
      });
      $('.contact-form-container').removeClass('hidden-mode');
      $('.messenger-contaner').addClass('stop-scroll');
      
  });

  $('.hide-contact').on('click', function(){
    $('.contact-form-container').addClass('hidden-mode');
    $('.messenger-contaner').removeClass('stop-scroll');
  });

  $('.inbox-message-send-msg-btn').on('click', function(){
    var messageToSend = $('.inbox-message-response-txt').val();
    $.ajax({
      url: '/saveMsg',
      method: 'POST',
      contentType: 'application/json',
      data: JSON.stringify({message: messageToSend, conversationId: convId}),
      success: function(response){
        alert('le message a bien ete enregistree');
      }
    });
  });
})

</script>

现在我可以发送消息并将它们存储在我的 mongoDB 中，但我需要刷新页面才能获取新消息...所以我尝试设置一个长轮询请求，但找不到解决方案，因为每次我在 jQuery 代码中设置了一个循环，它破坏了整个页面，并且无法再打开对话...如果有人可以帮助我改进我的代码并设置一个简单的无技术来获取消息而不刷新页面那就太好了!

抱歉我的英语不好!非常感谢您为我们而来!

Answer 1

如果您像您所说的那样对编程完全陌生，那么与其尝试从头开始创建您遇到问题的功能，也许使用可行的解决方案会是一个更好的主意。

您可以使用 Socket.io 来完成此类事情。它使用长轮询，并尝试升级到 WebSocket(如果支持)。使用起来非常简单。这是向客户端发送请求的服务器的完整工作示例:

var path = require('path');
var app = require('express')();
var http = require('http').Server(app);
var io = require('socket.io')(http);
app.get('/', (req, res) => {
  res.sendFile(path.join(__dirname, 'si.html'));
});
io.on('connection', s => {
  for (var t = 0; t < 3; t++)
    setTimeout(() => s.emit('message', 'message from server'), 1000*t);
});
http.listen(3002, () => console.error('listening on http://localhost:3002/'));

这是客户端上的完整 JavaScript 代码:

var l = document.getElementById('l');
var log = function (m) {
    var i = document.createElement('li');
    i.innerText = new Date().toISOString()+' '+m;
    l.appendChild(i);
}
log('opening socket.io connection');
var s = io();
s.on('connect_error', function (m) { log("error"); });
s.on('connect', function (m) { log("socket.io connection open"); });
s.on('message', function (m) { log(m); });

有关更多示例和更好的解释，请参阅 the project on GitHub我创建它是为了演示向客户端发送消息的用法。

另请参阅其他相关问题以了解更多详细信息:

• Differences between socket.io and websockets
• socket.io no communication between server and client
• why web socket behave differently on nodejs ?
• getting an error when trying to use socket.io
• How to use Socket.io combined with Express.JS