var normal_title;

document.addEventListener('visibilitychange',function(){ //浏览器切换事件

    if(document.visibilityState=='hidden') { //状态判断

        normal_title=document.title;

        document.title='隐藏的标题';

    }else {

        document.title=normal_title;

    }

});

document.addEventListener('visibilitychange',function(){

    if(document.visibilityState=='hidden') {

      if(ws){

        ws.close(); //关闭websocket

      }

    }else {

      location.reload(); //刷新页面

    }

  });