1、$("#demo").attr("style","display:none;");//隐藏div

   $("#demo").attr("style","display:block;");//显示div

2、$("#demo").css("display","none");//隐藏div

   $("#demo").css("display","block");//显示div

3、$("#demo").hide();//隐藏div

   $("#demo").show();//显示div

4、$("#demo").toggle(

       function () {

            $(this).attr("style","display:none;");//隐藏div

       },

       function () {

            $(this).attr("style","display:block;");//显示div

       }

   );
<div id="demo"></div>