WebSocket+node. js Create an Web chat server for instant messaging

This article example node. js to create instant messaging Web chat server, for your reference, the specific content is as follows

1. Use nodejs-websocket
nodejs-websocket is a backend library based on node. js to implement websocket protocol,
Connection: https://github.com/sitegui/nodejs-websocket.
(1) Installation
Install from the project directory via npm: npm install nodejs-websocket
(2) Create a server

 // Introduce nodejs-websocket
var ws = require( " nodejs-websocket " );
// Call createServer Method to create a server, and call back the conn Yes connection Example of 
var server = ws.create(function(conn){
  console.log( " New connection " );
  // Eavesdropping text Events, text Event is triggered whenever text type data is received from the server, and the argument of the callback function is the passed string 
  conn.on( " text " , function(str){
 console.log( " Received  "  + str);
  });
  // Eavesdropping close Event, which is triggered every time the connection is disconnected 
  conn.on( " close " , function(code, reason){
 console.log( " Connection closed " );
  })
}).listen(8888);

2. Client uses websocket
On the client side, you first need to instantiate an websocket object: ws = new WebSocket ("ws://localhost: 5000"); The parameter incoming format is ws://+ url, which is similar to http protocol prefix http://1. Next, you can monitor events and display data through one method built into websocket.
Here, the system 1 introduces each listening event: onopen is triggered when the server and the client establish a connection; onmessage triggers when the client receives the data sent by the server; onclose is triggered when the connection between the client and the server is closed; onerror triggers when a connection error occurs.

3. Use websocket + nodejs to realize online chat room
(1) html and css codes are omitted
(2) Client js:

oConnect.onclick=function(){
    ws=new WebSocket('ws://localhost:5000');
     ws.onopen=function(){
       oUl.innerHTML+="<li> Client is connected </li>";
     }
    ws.onmessage=function(evt){
      oUl.innerHTML+="<li>"+evt.data+"</li>";
    }
    ws.onclose=function(){
      oUl.innerHTML+="<li> Client disconnected </li>";
    };
    ws.onerror=function(evt){
      oUl.innerHTML+="<li>"+evt.data+"</li>";
 
    };
  };
  oSend.onclick=function(){
    if(ws){
      ws.send(oInput.value);
    }
  }(3) Server side js : 
 /*
websocket Two types of data transfer are supported: text Type and binary Type, where 2 The binary data is sent and read through the stream mode 
*/
var app=require('http').createServer(handler); // To simplify the code, put the specific code created by the server into handler In a function 
var ws=require('nodejs-websocket');
var fs=require('fs');
app.listen(8888);
function handler(req,res){
  //__dirname Returns the current directory where the file is located. Call readFile Method to read files 
  fs.readFile(__dirname+'/index.html',function(err,data){
    if(err){
      res.writeHead(500);
      return res.end('error ');
    }
    res.writeHead(200);
    res.end(data);
  });
}
// The above steps are successful in 8888 Port to render the corresponding html Interface 
//conn Is corresponding to connection Example of 
var server = ws.createServer(function(conn){
  console.log('new conneciton');
  // Eavesdropping text Event that is triggered whenever text is received 
  conn.on("text",function(str){
    broadcast(server,str);
  });
  // When any 1 Triggered when the terminal closes the connection, which is the output in the console connection closed
  conn.on("close",function(code,reason){
    console.log('connection closed');
  })
}).listen(5000);
// Pay attention to the listen Listening is the port of the server just opened, and the client sends messages here for processing 
 
function broadcast(server, msg) {
  //server.connections Yes 1 An array containing all connected clients 
  server.connections.forEach(function (conn) {
    //connection.sendText Method can send the specified content to the client, passing in 1 String 
    // Here is traversing every 1 Clients send content for it 
    conn.sendText(msg);
  })
}

 That's the article