CSS Layer Click-Through

In this article, we’ll explain how to implement layer click-through using CSS and provide examples to help you understand.

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What is Layer Clickthrough?

In CSS, layer clickthrough means that when one element is overlaid on top of another, mouse clicks pass through the top element and directly affect the underlying element. This allows us to create interesting effects on the page, such as clicking a transparent overlay to trigger a button underneath.

CSS Pointer Events in

Before understanding layer click-through, we need to first understand pointer events in CSS. There are four CSS properties related to pointer events: pointer-events, cursor, touch-action, and will-change.

The pointer-events Property

The pointer-events property defines how an element responds to pointer events. Common values ​​are as follows:

• auto: The default value, which means the element responds to pointer events;
• none: The element does not respond to pointer events; the events are passed down to the next element in the hierarchy;
• inherit: Inherits the value of the parent element’s pointer-events property.

cursor Property

cursor property defines the shape of the mouse pointer over an element. When an element responds to pointer events, it is often used to change the cursor’s style to indicate that the user can interact with the element.

touch-action Property

touch-action property specifies whether a given element is user-interactive. Common values ​​are as follows:

• auto: Default value, element is user-interactive;
• none: Element is not user-interactive; events are passed down to the next level;
• manipulation: Element is user-interactive, but default browser gestures such as scrolling and zooming are blocked.

The will-change Attribute

The will-change attribute specifies the properties of an element that will change, allowing the browser to perform optimizations for that element, such as creating layers.

Methods for Implementing Click-Through Layers

Click-through layers can be implemented in two ways: using the pointer-events attribute and using event.target.

Using the pointer-events property

By setting the top-level element’s pointer-events property to none can make the element not respond to pointer events and pass the events transparently to the underlying elements. Here’s an example:

<style> 
#top-layer { 
position: absolute; 
width: 200px; 
height: 200px; 
background-color: rgba(0, 0, 0, 0.5); 
pointer-events: none; 
cursor: pointer; 
} 

#bottom-layer { 
position: absolute; 
top: 50px; 
left: 50px; 
width: 100px; 
height: 100px; 
background-color: #ff0000; 
} 

</style> 
<div id="top-layer"></div> 
<div id="bottom-layer"></div> 

In this example, #top-layer The #bottom-layer is a transparent overlay layer, and the #bottom-layer is a red square underneath it. Because the pointer-events property of the #top-layer is set to none, when a user clicks the overlay layer, they actually click the red square underneath, triggering the click event bound to the #bottom-layer.

Using event.target

Another way to achieve layer click-through is to use event.target. When a click event is bound to an element and the click occurs on an element below it, you can use event.target to retrieve the actual clicked element, simulating a layer click-through effect. Here’s an example:

<style> 
#top-layer { 
position: absolute; 
width: 200px; 
height: 200px; 
background-color: rgba(0, 0, 0, 0.5); 
cursor: pointer; 
} 

#bottom-layer { 
position: absolute; 
top: 50px; 
left: 50px; 
width: 100px; 
height: 100px; 
background-color: #ff0000; 
} 

</style> 
<div id="top-layer" onclick="handleClick(event)"></div> 
<div id="bottom-layer"></div> 
<script> 
function handleClick(event) { 
if (event.target.id === 'top-layer') {
// Handle click events
console.log('Clicked the overlay');
} else {
console.log('Clicked the underlying element');
}
}
</script>

In this example, when a user clicks the overlay, by checking the id of event.target, we can determine whether the user actually clicked the overlay or the underlying element and execute the corresponding logic.

Summary

In this article, we introduced how to implement layer click-through effects in CSS. By using the pointer-events property or event.target, we can achieve some special interactive effects on the page. We hope these examples will help you better understand the concept and implementation of layer click-through.