How to implement navigation menu in javascript

JavaScript is a front-end programming language that is widely used in web development because of its lightweight, efficient, easy to learn and use characteristics. In web design, navigation menu is an essential component that makes the content of the website more organized and accessible. In this article, we will introduce how to implement a simple navigation menu using JavaScript.

1. HTML

First, we need to create a container in HTML to store the navigation menu. This container can be a ul element or a div element. In this article, we will use the ul element to implement a navigation menu.

<ul id="nav">
    <li><a href="#">首页</a></li>
    <li><a href="#">新闻中心</a></li>
    <li><a href="#">产品中心</a></li>
    <li><a href="#">联系我们</a></li>
</ul>

2. CSS

Next, we need to style the navigation menu. This includes menu item color, size, margins, etc. In this article, we need to set the background color of menu items on mouseover as well as the style of the currently selected menu item.

#nav {
    list-style: none;
    margin: 0;
    padding: 0;
}

#nav li {
    float: left;
    margin: 5px;
}

#nav a {
    display: block;
    padding: 5px;
    color: #333;
    text-decoration: none;
    background-color: #eee;
}

#nav a:hover {
    background-color: #999;
    color: #fff;
}

#nav .current a {
    background-color: #999;
    color: #fff;
}

In the above code, we define the style of the navigation menu under #nav, and the style of the menu items under #nav li and #nav a. We use the float attribute to arrange the menu items horizontally, and the margin attribute to set the margins of the menu items. When the mouse hovers over the menu item, we change its background color to gray and the text color to white; and when the menu item is selected, we change its background color to black and the text color to White.

3. JavaScript

Finally, we need to use JavaScript to implement the click event of the menu item. We need to set the currently selected menu item to the .active style and remove the .active style from the previously selected menu item. We can use the document.getElementById() method to get the menu items, and then use the classList.add() and classList.remove() methods to add or remove styles.

var nav = document.getElementById('nav');
var links = nav.getElementsByTagName('a');

for (var i = 0; i < links.length; i++) {
    links[i].addEventListener('click', function() {
        for (var j = 0; j < links.length; j++) {
            links[j].parentNode.classList.remove('active');
        }
        this.parentNode.classList.add('active');
    });
}

In the above code, we first obtain the parent element #nav of the menu item and all menu items a, and then use a for loop to add a click event to each menu item. When a menu item is clicked, we first use a for loop to remove the .active style of the previously selected menu item, and then add the .active style of the currently selected menu item.

4. Complete code

Finally, combine the HTML, CSS and JavaScript code to get the complete navigation menu implementation code.

<ul id="nav">
    <li><a href="#">首页</a></li>
    <li><a href="#">新闻中心</a></li>
    <li><a href="#">产品中心</a></li>
    <li><a href="#">联系我们</a></li>
</ul>

#nav {
    list-style: none;
    margin: 0;
    padding: 0;
}

#nav li {
    float: left;
    margin: 5px;
}

#nav a {
    display: block;
    padding: 5px;
    color: #333;
    text-decoration: none;
    background-color: #eee;
}

#nav a:hover {
    background-color: #999;
    color: #fff;
}

#nav .current a {
    background-color: #999;
    color: #fff;
}

var nav = document.getElementById('nav');
var links = nav.getElementsByTagName('a');

for (var i = 0; i < links.length; i++) {
    links[i].addEventListener('click', function() {
        for (var j = 0; j < links.length; j++) {
            links[j].parentNode.classList.remove('active');
        }
        this.parentNode.classList.add('active');
    });
}

The above is the complete code for using JavaScript to implement the navigation menu. You can apply it to your own website to help users better browse the website content.

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