如何 - 向下滑动滚动条

了解如何使用 CSS 和 JavaScript 在滚动条上向下滑动导航栏。

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如何滑下酒吧

步骤1）添加HTML：

创建导航栏：

示例

<div id="navbar">
<a href="#home">Home</a>
<a href="#news">News</a>
<a href="#contact">Contact</a>
</div>

步骤2）添加CSS：

导航栏样式：

示例

#navbar {
  background-color: #333; /* Black background color */
  position: fixed; /* Make it stick/fixed */
  top: -50px; /* Hide the navbar 50 px outside of the top view */
  width: 100%; /* Full width */
  transition: top 0.3s; /* Transition effect when sliding down (and up) */
}

/* Style the navbar links */
#navbar a {
  float: left;
  display: block;
  color: white;
  text-align: center;
  padding: 15px;
text-decoration: none;
}

#navbar a:hover {
  background-color: #ddd;
  color: black;
}

步骤 3) 添加 JavaScript：

示例

// When the user scrolls down 20px from the top of the document, slide down the navbar
// When the user scrolls to the top of the page, slide up the navbar (50px out of the top view)
window.onscroll = function() {scrollFunction()};

function scrollFunction() {
if (document.body.scrollTop > 20 || document.documentElement.scrollTop > 20) {
document.getElementById("navbar").style.top = "0";
} else {
document.getElementById("navbar").style.top = "-50px";
}
}

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