javascript - JQuery 窗口滚动顶部和底部

Question

我能够在滚动到底部时加载我的ajax，我试图弄清楚如何修改下面的代码片段，以便它仅在窗口滚动到顶部时才起作用？

 $(window).scroll(function () {
    if ($(document).height() <= $(window).scrollTop() + $(window).height()) {
       //this works here for scrolling bottom
    }
    else if ($(document).height() >= $(window).scrollTop() + $(window).height()){

        //i tried checking for greater than the window scroll but that didn't owrk
    }
});

Answer 1

当 scrollTop() 返回滚动条的垂直位置 0 表示滚动条位于顶部位置。

$(window).scroll(function () {
    if ($(window).scrollTop() == 0){
        alert("Up");
    }
});

或者您可以按如下方式更新代码，

$(window).scroll(function () {
    if ($(window).scrollTop() + $(window).height() < $(document).height()){
        alert("Up");
    //i tried checking for greater than the window scroll but that didn't work
    }
});