How to prevent page scrolling behind mask layer

.ovfHiden{overflow: hidden;height: 100%;}

$(".header_right").click(function(){$('html,body').addClass('ovfHiden'); //使网页不可滚动
   $(".searchbox").show();
 })
 $(".yg-close").click(function(){
   $('html,body').removeClass('ovfHiden'); //使网页恢复可滚
   $(".searchbox").hide();
 })

document.documentElement.style.overflow = "hidden";

document.documentElement.style.overflow = "scroll";

var top_temp = $(document).scrollTop()||document.documentElement.scrollTop || document.body.scrollTop;
window.parent.scrollTo(0,top_value);