向下滚动或向上滚动时如何显示或隐藏菜单？

Question

当我向下滚动以隐藏此菜单时以及当我向上滚动以显示此菜单时.

我的菜单机器人是:

<script>
            var previousScroll = 0;
            $(window).scroll(function(event){
               var scroll = $(this).scrollTop();
               if (scroll > previousScroll){
                   $("menu-footer").filter(':not(:animated)').slideUp();
               } else {
                  $("menu-footer").filter(':not(:animated)').slideDown();
               }
               previousScroll = scroll;
            });
    </script>

    <section id="menu-footer">
        <ul>
            <li>
                <li><a href="javascript:history.back()"><i class="fa fa-arrow-circle-left"></i><?php _e("Back", ET_DOMAIN); ?></a></li>
            </li>
            <li>
                <a class="<?php echo $nearby_active; ?>" href="#" id="search-nearby"><i class="fa fa-compass"></i><?php _e("Nearby", ET_DOMAIN); ?></a>
                <form id="nearby" action="<?php echo get_post_type_archive_link('place')  ?>" method="get" >
                    <input type="hidden" name="center" id="center_nearby" />
                </form>
            </li>
            <!--<li><a href="#"><i class="fa fa-plus"></i>Submit</a></li>-->
            <!--<li>
                <a class="<?php echo $review_active; ?>" href="<?php echo et_get_page_link('list-reviews') ?>">
                    <i class="fa fa-comment"></i><?php _e("Reviews", ET_DOMAIN); ?>
                </a>
            </li>-->
            <li><a class="<?php echo $post-place; ?>" href="<?php echo et_get_page_link('post-place')?>"><i class="fa fa-flag-checkered"></i><?php _e("Post an Ad", ET_DOMAIN); ?></a></li>
            <?php if(has_nav_menu('et_mobile_header')) { ?>
            <li>
                <li><a href="#" class="search-btn"><i class="fa fa-search-plus"></i><?php _e("Search", ET_DOMAIN); ?></a></li>
            </li>       
            <li>                
                <a href="javascript:history.back()"><i class="fa fa-refresh"></i><?php _e("Refresh", ET_DOMAIN); ?></a>
            </li>
            <?php } ?>
        </ul>
    </section>

上面的脚本是我尝试用来隐藏菜单的.我的菜单页脚的CSS是:

#menu-footer {
    width: 100%;
    background: #5f6f81;
    position: fixed;
    bottom: 0;
    transition: top 0.2s ease-in-out;
    z-index: 100
}

我想让这个脚本工作的是什么？如果你有另一个解决方案,那将会很有帮助.

Answer 1

我在普通的Javascript中创建了第一个示例,以便通过快速查看代码来轻松理解.它隐藏了菜单,根据滚动条的位置(当滚动条距离顶部超过0个像素时)更改CSS样式的"底部"属性(从0到-100).如果滚动条返回顶部(0px),菜单将再次显示(从-100到0).CSS过渡效果可以动画更改:

window.addEventListener("scroll", bringmenu);

function bringmenu() {
    if (document.body.scrollTop > 0 || document.documentElement.scrollTop > 0) {
        document.getElementById("bottommenu").style.bottom = "-100%";
    } else {
        document.getElementById("bottommenu").style.bottom = "0";
    }
}

body {
  margin: 0;
  background: lavender;
}

#bottommenu {
  position: fixed;
  bottom: 0;
  width: 100%;
  height: auto;
  background: tomato;  
  -webkit-transition: bottom 2s;
  transition: bottom 2s;
}

<div id=content>
<p>content</p><p>content</p><p>content</p><p>content</p><p>content</p><p>content</p><p>content</p><p>content</p><p>content</p><p>content</p><p>content</p><p>content</p><p>content</p><p>content</p><p>content</p><p>content</p><p>content</p><p>content</p><p>content</p><p>content</p>
</div>

<div id=bottommenu>
<span>bottom </span><span>bottom </span><span>bottom </span><span>bottom </span><br><span>bottom </span><span>bottom </span><span>bottom </span><span>bottom </span>
</div>

更新:根据评论的要求,第二个片段在向上/向下滚动时带来/隐藏菜单,无论栏的当前位置如何(为了找到方向,当滚动被激活时,它将当前位置与先前位置进行比较然后存储要在下一个滚动事件中进行比较的变量中的当前位置):

var lastScrollTop = 0;

window.addEventListener("scroll", function(){  
   var st = window.pageYOffset || document.documentElement.scrollTop;  
   if (st > lastScrollTop){
       document.getElementById("bottommenu").style.bottom = "-100%";
   } else {
      document.getElementById("bottommenu").style.bottom = "0";
   }
   lastScrollTop = st;
}, false);

body {
  margin: 0;
  background: honeydew;
}

#bottommenu {
  position: fixed;
  bottom: 0;
  width: 100%;
  height: auto;
  background: hotpink;  
  -webkit-transition: bottom 2s;
  transition: bottom 2s;
}

<div id=content>
<p>content</p><p>content</p><p>content</p><p>content</p><p>content</p><p>content</p><p>content</p><p>content</p><p>content</p><p>content</p><p>content</p><p>content</p><p>content</p><p>content</p><p>content</p><p>content</p><p>content</p><p>content</p><p>content</p><p>content</p>
</div>

<div id=bottommenu>
<span>bottom </span><span>bottom </span><span>bottom </span><span>bottom </span><br><span>bottom </span><span>bottom </span><span>bottom </span><span>bottom </span>
</div>

滚动方向代码由@Prateek

Answer 2

基本上你需要使用 3 个主要想法来实现这一点。

1. 将菜单/标题设置为固定。
2. 向下滚动时，添加一个类以删除标题/菜单。
3. 向上滚动时，删除隐藏标题/菜单的类。

这是 Marius Craciunoiu 的演示

网页：

<header class="nav-down">
    This is your menu.
</header>
<main>
    This is your body.
</main>
<footer>
    This is your footer.
</footer>

JavaScript：

// Hide Header on on scroll down
var didScroll;
var lastScrollTop = 0;
var delta = 5;
var navbarHeight = $('header').outerHeight();

$(window).scroll(function(event){
    didScroll = true;
});

setInterval(function() {
    if (didScroll) {
        hasScrolled();
        didScroll = false;
    }
}, 250);

function hasScrolled() {
    var st = $(this).scrollTop();

    // Make sure they scroll more than delta
    if(Math.abs(lastScrollTop - st) <= delta)
        return;

    // If they scrolled down and are past the navbar, add class .nav-up.
    // This is necessary so you never see what is "behind" the navbar.
    if (st > lastScrollTop && st > navbarHeight){
        // Scroll Down
        $('header').removeClass('nav-down').addClass('nav-up');
    } else {
        // Scroll Up
        if(st + $(window).height() < $(document).height()) {
            $('header').removeClass('nav-up').addClass('nav-down');
        }
    }

    lastScrollTop = st;
}

CSS：

   body {
    padding-top: 40px;
}

header {
    background: #f5b335;
    height: 40px;
    position: fixed;
    top: 0;
    transition: top 0.2s ease-in-out;
    width: 100%;
}

.nav-up {
    top: -40px;
}

main {
   background:url(
data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAoAAAAKCAYAAACNMs+9AAAAPklEQVQYV2O8dOnSfwYg0NPTYwTRuAAj0QqxmYBNM1briFaIzRbi3UiRZ75uNgUHGbfvabgfsHqGaIXYPAMAD8wgC/DOrZ4AAAAASUVORK5CYII=
   ) repeat;
    height: 2000px;
}

footer { background: #ddd;}
* { color: transparent}