通过websocket，服务器可以主动给客户端发消息，并且不需要每次都http请求一下，下面是我写的一个简单小程序；
- 服务器端node.js
var app = require('express')();
var http = require('http').Server(app);
var io = require('socket.io')(http);
app.get('/', function(req, res){
res.send('<h1>Welcome Realtime Server</h1>');
});
io.on('connection', function(socket){
console.log('a user connected');
//连接后定时发送信息
setInterval(function(){
io.emit('message', "正在连接");
},2000);
//监听用户发布聊天内容
socket.on('message', function(obj){
//向所有客户端广播发布的消息
io.emit('message', obj);
console.log(obj.username+'说：'+obj.content);
});
});
http.listen(3000, function(){
console.log('listening on *:3000');
});
- 前端展示
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<script src="https://cdnjs.cloudflare.com/ajax/libs/socket.io/2.1.0/socket.io.dev.js"></script>
<title>实时定位结果展示</title>
</head>
<body>
<script src="./js/index.js"></script>
<script>
var socket
= io.connect('ws://localhost:3000');
socket.on('connect', function () {
//连接成功
console.log("success");
});
socket.on('disconnect', function (data) {
//连接断开
console.log("disconnect");
});
socket.on('message', function (data) {
console.log(data);
});
</script>
</body>
</html>
运行结果如下图：网页端后台一直输出消息
