index_socket.html

<!DOCTYPE html>
<html>
        
<head>
     <meta charset="utf-8"/>
    <title>socket</title>
</head>

<body>


<button id="sendBtn">发送消息</button>

<button id="leaveBtn">离开</button>

</body>
<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/socket.io/2.0.4/socket.io.js"></script>
<script type="text/javascript">
    var socket=io.connect('http://127.0.0.1:3001'),//与服务器进行连接
        send=document.getElementById('sendBtn'),
        leave=document.getElementById('leaveBtn');


    send.onclick=function(){

        socket.send('hello world!hello worldhello worldhello world'); 
        socket.emit('hi', 'hello!');

    }

    leave.onclick=function(){
        window.location.href="about:blank";
        window.close()
        socket.emit('leave', 'leave');
    }

    //接收来自服务端的信息事件c_hi
    socket.on('c_hi',function(msg){
       console.log(msg);
    })

    // socket.on('c_leave',function(msg){
    //     alert(msg)
    // })

</script>

</html>