Question

如果用户滚动到顶部，如何才能重新显示导航栏？目前，当用户向上滚动时，导航栏出现，与屏幕的位置无关。

Html

<header class="nav-down">
 <div> navigation </div>
</header>

Javascript

var didScroll;
var lastScrollTop = 0;
var delta = 5;
var navbarHeight = $('#navigation-container').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('navigation-container').addClass('nav-up');
} else {
    // Scroll Up
    if(st + $(window).height() < $(document).height()) {
        $('header').removeClass('nav-up').addClass('nav-down');
    }
}

lastScrollTop = st;
}

CSS

header {
height: 40px;
position: fixed;
top: 0;
transition: top 0.5s ease-in-out;
width: 100%;
z-index: 999;
padding-top: 50px;
}

.nav-up {
top: -70px;
}

谢谢！

Answer 1

要实现这一目标，您需要做两件事：

删除/评论整个导航栏脚本。
通过删除除以下两行之外的所有内容来清除CSS中的header { height: 40px; width: 100%; }声明：

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>

<groupId>com.mycompany.app</groupId>
<artifactId>my-app</artifactId>
<version>1.0-SNAPSHOT</version>
<packaging>jar</packaging>

<name>Maven Quick Start Archetype</name>
<url>http://maven.apache.org</url>

    <dependencies>
        <dependency>
            <groupId>org.xerial</groupId>
            <artifactId>sqlite-jdbc</artifactId>
            <version>3.16.1</version>
        </dependency>
    </dependencies>

</project>

如何使导航栏仅显示在最顶层？

1 个答案: