JavaScriptCSS menu function Ultimate Edition _ navigation menu

In the previous article titled JavaScriptcss menu function implementation, the menu function was simply implemented through an HTML page. However, in actual development, if there are many items in the menu bar and HTML modification is frequent, it will be cumbersome and error-prone. The improved version optimizes this problem and adds menus through simple Javascript code. At the same time, the HTML page is very concise. You only need to write two lines of code! O (partition _ partition) O
1. Prerequisite: Introduce a CSS file and a JavaScript file to the HTML page. As follows:

The Code is as follows:

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