The key to making the drop-down menu is the coordination of HTML structure with CSS and JS. First, use the unordered list
<ul> and <li> to build the infrastructure, and the main menu item contains nested submenu <ul>; then set the submenu by default to hide (display: none), use the :hover pseudo-class to achieve hover display, and use position: absolute to locate the submenu; finally, to be compatible with the mobile terminal, JavaScript needs to add click events to switch the submenu status, and pay attention to handling detailed issues such as link jumps and hierarchical display.It is actually not difficult to make a drop-down menu, the key lies in the coordination of structure and interaction. Using HTML to match the structure, combined with a little CSS and JS (if dynamic effects are required), you can create a practical drop-down menu.

Infrastructure: How to write HTML part
The basis of the drop-down menu is the unordered list <ul></ul>
and the list item <li>
. Typically, the main menu item is a link or button, while the submenu is nested in another <ul></ul>
. For example:

<ul class="dropdown-menu"> <li><a href="#">Main Menu Item</a> <ul> <li><a href="#">Submenu1</a></li> <li><a href="#">Submenu 2</a></li> </ul> </li> </ul>
The key here is to express hierarchical relationships through nesting <ul>
. This not only makes the semantics clear, but also makes it easier to use CSS to control display and hide.
Style control: Use CSS to achieve basic pull-down effect
HTML alone is not enough, CSS is responsible for controlling appearance and interaction logic. You have to do at least a few things:

display: none
)<li> Display submenu when the mouse is hovered (using :hover
pseudo-class)<li> Set the appropriate positioning method to make the submenu appear in the correct positionThe sample code is as follows:
.dropdown-menu ul { display: none; position: absolute; top: 100%; left: 0; } .dropdown-menu li:hover > ul { display: block; }
This style causes the submenu to appear when the mouse is hovered and positioned below the main menu item. You can adjust the position and style according to the actual layout.
Advanced skills: Support click expansion (mobile-side compatible)
The above method performs well on the desktop, but it is not very effective on the mobile side. Because the mobile terminal does not have the concept of "hover", JavaScript needs to be used to simulate the click-and-expand behavior.
The idea is very simple: bind the click event to the main menu item and switch the display status of the submenu. You can control it with class names or directly operate the style.
document.querySelectorAll('.dropdown-menu > li').forEach(item => { item.addEventListener('click', function(e) { const submenu = this.querySelector('ul'); if (submenu) { e.preventDefault(); submenu.classList.toggle('active'); } }); });
Then add a .active
class to CSS to control the display:
.dropdown-menu ul.active { display: block; }
This will work normally on both mobile phones and computers.
Don't ignore small details
<ul> <li>position: absolute
is very important, otherwise it will expand the page layout
<li> If the main menu item itself is a link, please note that the clicking behavior may jump to the page. Remember to use e.preventDefault()
to handle it.
<li> In multi-level menus, pay attention to hierarchy issues. You may need to use z-index
to ensure that the submenu is displayed at the top level
Basically that's it. Implementing a basic drop-down menu is not complicated, but to make good compatibility and smooth experience, you still have to pay attention to a lot of details.
The above is the detailed content of How to create a dropdown menu in HTML?. For more information, please follow other related articles on the PHP Chinese website!

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