Question

怎么设置返回顶部的js代码 当到达顶部时消失

$('html,body').animate({
scrollTop:0
} ,800)

})
$(window).on('scroll', function()
{
if ($(window).scrollTop() > $(window).height())

backButton.fadeIn();

})
$(window).trigger('scroll');
为什么进入页面不显示返回顶部标签了

Answer 1

if ( i <= 20) {$("#gotop").css("display","none");}else if (i > 21) {$("#gotop").css("display","block");}