JS实现websocket长轮询实时消息提示的效果

<%@ page contentType="text/html;charset=UTF-8" language="java"%><div class="page-header navbar navbar-fixed-top">  <div class="page-header-inner">    <div class="page-logo">      <a href="<c:url value=" rel="external nofollow" rel="external nofollow" /"/>"><img        src="<c:url value="/img/logo.png"/>" style="height: 14px" alt="logo"        class="logo-default" /></a>      <div class="menu-toggler sidebar-toggler hide"></div>    </div>    <a href="javascript:;" rel="external nofollow" rel="external nofollow" class="menu-toggler responsive-toggler"      data-toggle="collapse" data-target=".navbar-collapse"></a>    <div class="top-menu">      <ul class="nav navbar-nav pull-right">        <li class="dropdown dropdown-alert"><a href="#" rel="external nofollow" rel="external nofollow"           class="dropdown-toggle" data-toggle="dropdown"          data-hover="dropdown" data-close-others="true"> <span            class="badge pull-left"></span><label class="hidden-sm">报警</label><i            class="fa fa-bell"></i>        </a>          <ul class="dropdown-menu">          </ul></li>        <li class="dropdown dropdown-user"><a href="#" rel="external nofollow" rel="external nofollow"           class="dropdown-toggle" data-toggle="dropdown"          data-hover="dropdown" data-close-others="true"> <span            class="username username-hide-on-mobile">你好，${sessionScope.username}</span>            <i class="fa fa-angle-down"></i>        </a>          <ul class="dropdown-menu">            <li><a href="javascript:;" rel="external nofollow" rel="external nofollow" id="updatePass"><i                class="icon-lock"></i>修改密码</a></li>            <li><a href="<c:url value=" rel="external nofollow" rel="external nofollow" /logout"/> "><i                class="icon-key"></i>退出登录</a></li>          </ul></li>      </ul>    </div>  </div></div><div class="clearfix"></div><script>  //toastr.sos(num1)</script><script type="text/javascript"  src="http://cdn.bootcss.com/jquery/3.1.0/jquery.min.js"></script><script type="text/javascript"  src="http://cdn.bootcss.com/sockjs-client/1.1.1/sockjs.js"></script><script type="text/javascript">  function wsPath() {    var pathName = window.document.location.pathname;    var host = window.location.host;    var projectName = pathName.substring(0,        pathName.substr(1).indexOf('/') + 1);    return (host + projectName);  }  wsPath = wsPath();  var websocket = null;  if ('WebSocket' in window) {    websocket = new WebSocket("ws://" + wsPath + "/websocket/socketServer");  } else if ('MozWebSocket' in window) {    websocket = new MozWebSocket("ws://" + wsPath        + "/bison/websocket/socketServer");  } else {    websocket = new SockJS("http://" + wsPath        + "/bison/sockjs/socketServer");  }  websocket.onmessage = onMessage;  websocket.onope = onOpen;  websocket.onerror = onError;  websocket.onclose = onClose;  function onOpen() {  }  function onMessage(evt) {    var $uncheckedAlertMenuBtn = $("a.dropdown-toggle", $uncheckedAlertMenu);    var $uncheckedAlertBadge = $("span.badge", $uncheckedAlertMenuBtn);    var $uncheckedAlertMenu = $('li.dropdown-alert');    var $uncheckedAlertList = $('ul', $uncheckedAlertMenu);    var a = $uncheckedAlertBadge.html();    $uncheckedAlertBadge.html(Number(a) + 1);    //判断报警类型 如果是位置偏移，place+1    if (evt.data == "1") {      var count;      var a = $("#number").html();      if (a == null) {        count = 1;        $uncheckedAlertList            .prepend('<li class="place-alert"><a href="alert?menuId=274" rel="external nofollow" rel="external nofollow" > <font color="red" id="place-alert">'                + "位置报警(<font id ='number'>"                + count                + "</font>)" + '</font></a></li>');      } else {        count = Number(a) + 1;        $("#place-alert").html(            "位置偏移(<font id='number'>" + count + "</font>)");      }    }    if (evt.data == "0") {      var count;      var a = $("#snum").html();      if (a == null) {        count = 1;        $uncheckedAlertList            .prepend('<li class="sos-alert"> <a href="alert?menuId=274" rel="external nofollow" rel="external nofollow" ><font color="red" id="sos-alert">'                + "SOS报警(<font id='snum'>"                + count                + ")</font>"                + '</font></a></li>');      } else {        count = Number(a) + 1;        $("#sos-alert").html(            "SOS报警(<font id='snum'>" + count + "</font>)");      }    }  }  function onError() {    websocket.close();  }  function onClose() {  }  window.close = function() {    websocket.onclose();  }</script>