Why Do CSS Transitions Fail To Work With the Visibility Property?

CSS Transitions and Visibility: A Deceptive Illusion

In CSS, transitions allow for smooth animations between property states. However, a puzzling issue arises when attempting to transition visibility, leaving users perplexed and wondering if it's a bug.

The Case of Visibility Transition

Consider the following code:

<code class="css">#inner {
    visibility: hidden;
    transition: visibility 1000ms;
}

#outer:hover #inner {
    visibility: visible;
}</code>

This code aims to reveal the element with the ID "inner" upon hovering over the element with the ID "outer." However, to our dismay, the transition fails to operate as expected. Instead of a smooth transition, visibility abruptly toggles after a delay, which matches the specified transition duration.

The Culprit

The root cause lies in the nature of the visibility property. Unlike properties such as opacity, which represent continuous values (0-1), visibility exists in a binary state (visible or hidden). This fundamental difference hampers transitions, as there are no intermediate states to interpolate.

Transitionable Properties

Transitions rely on calculating keyframes between two numerical values. In the case of opacity, the transition smoothly fades between 0 and 1. However, with visibility, the transition lacks the necessary numerical range to interpolate.

Conclusion

While initially resembling a bug, this behavior is an inherent limitation of CSS transitions. Only properties with calculable values can be smoothly animated. For binary properties like visibility, abrupt state changes are inevitable.

The above is the detailed content of Why Do CSS Transitions Fail To Work With the Visibility Property?. For more information, please follow other related articles on the PHP Chinese website!