index.html

<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet"
      integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u" crossorigin="anonymous">
<header class="entry-header fading" style="text-align:center">
    <h1 class="entry-title">Socket.io + Node.js + Mysql</h1>

    <form method="post" action="sendmsgdata" enctype="multipart/form-data">
        <input type="text" id="msg" name="msg"><br>
        <input type="file" id="img" name="img"><br>
        <button type="submit">send</button>
    </form>

    <input type="text" id="uid"><br>
    <input type="button" value="done" id="ubtn"><br>

    <input type="text" id="rid"><br>
    <input type="button" value="done" id="rbtn">
</header>

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/socket.io/2.0.3/socket.io.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"
        integrity="sha384-Tc5IQib027qvyjSMfHjOMaLkfuWVxZxUPnCJA7l2mCWNIpG9mGCD8wGNIcPD7Txa"
        crossorigin="anonymous"></script>
<script>
    $(document).ready(function () {
        $('#rbtn').click(function () {
            socket.emit('request', {action: "Demorclick", data: {userid: $('#uid').val(), reciverid: $('#rid').val()}});
        });
        $('#ubtn').click(function () {
            socket.emit('request', {action: "Connection", data: {userid: $('#uid').val()}});
            socket.emit('request', {action: "GetChatUserList", data: {userid: $('#uid').val()}});
        });
    });
    var socket = io.connect('http://' + window.location.hostname + ':8000');
    socket.emit('request', {action: "Connection", data: {userid: 3}});
    socket.on('UserList', function (data) {
        console.log(data);
    });
    socket.on('response', function (data) {
        console.log(data);
    });
    //socket.emit('request',{action:"GetChatUserList",data:{userid:"3"}});
</script>