How to use JavaScript to show and hide the fixed navigation bar at the bottom of the web page?

How to use JavaScript to show and hide the fixed navigation bar at the bottom of the web page?

In web design, fixed navigation bar is a common design element, which can provide users with quick navigation functions to access the website. When the user scrolls the page, the navigation bar can be fixed at the bottom of the page to provide continuous navigation services. This article explains how to achieve this effect using JavaScript and provides specific code examples.

To achieve the display and hiding effect of the fixed navigation bar at the bottom of the web page, it can be divided into the following steps:

Step 1: HTML structure
First, create a navigation bar in the HTML file A container element, such as a div tag, and set an id so that it can be manipulated using JavaScript.

<div id="navbar" class="navbar">
  <!-- 导航栏的内容 -->
</div>

Step 2: CSS style
Set CSS style for the navigation bar, such as setting fixed positioning, bottom alignment and other properties. This ensures that the navigation bar is always at the bottom of the page.

.navbar {
  position: fixed;
  bottom: 0;
  width: 100%;
  /* 其它样式属性 */
}

Step 3: JavaScript code
To implement the display and hide effect of the navigation bar, you need to monitor the page scroll event and determine whether the navigation bar is displayed based on the scroll position of the page.

// 获取导航栏元素
var navbar = document.getElementById("navbar");

// 监听页面滚动事件
window.addEventListener("scroll", function() {
  // 获取页面滚动的高度
  var scrollHeight = window.pageYOffset || document.documentElement.scrollTop || document.body.scrollTop;
  
  // 设置导航栏的显示或隐藏
  if (scrollHeight > 200) {
    navbar.style.display = "none";
  } else {
    navbar.style.display = "block";
  }
});

In the above code, we first obtain the navigation bar element through the document.getElementById method, and then use the window.addEventListener method to listen for page scroll events. In the event handler function, we get the height of the page scroll, and then determine whether to display the navigation bar based on the height, and achieve the display or hide effect by modifying the style.display attribute of the navigation bar element.

It should be noted that scrollHeight > 200 in the above code is an example judgment condition and can be adjusted according to actual needs. When the page scroll height is greater than 200, the navigation bar is hidden; otherwise, the navigation bar is displayed.

Step 4: Complete the effect
Finally, introduce the above HTML, CSS and JavaScript code into the page to complete the display and hide effect of the fixed navigation bar at the bottom of the web page.

Summary
This article introduces how to use JavaScript to realize the display and hiding effect of the fixed navigation bar at the bottom of the web page. By listening to the page scroll event and judging whether the navigation bar is displayed based on the scroll position of the page, a simple and practical effect can be achieved. Of course, according to actual needs, we can further expand and optimize this effect, such as adding animation effects, changing the style of the navigation bar, etc. I hope this article can be helpful to everyone!

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