Animated Position of Focus Ring

FocusOverlay, a library created by Maurice Mahan, is used to create animated focus rings on elements that get focus. It is similar to the Flying Focus philosophy, highlighting the movement of the focus elements through animation effects.

The utility of this library is controversial in terms of accessibility:

• Advantages: The animation effect clearly indicates the change in the focus position, especially when the page is scrolling, it can guide users to pay more effectively to the focus.
• Disadvantages: Additional animation effects may cause interference or discomfort to some users, especially those who are sensitive to movement.

Additionally, the library needs to control behavior through data attributes, which may lead to developers needing to add extra code to the template. To solve this problem, it is recommended to load the library conditionally according to the user's "reduce motion" preferences.

The FocusOverlay library can be obtained on npm and also supports direct linking through UNPKG. The following code demonstrates how to conditionally load a library based on user preferences:

<link href="//unpkg.com/focus-overlay@latest/dist/focusoverlay.css" media="prefers-reduced-motion: no-preference" rel="stylesheet">
<script>
const mq = window.matchMedia("(prefers-reduced-motion: no-preference)");

if (mq.matches) {
  let script = document.createElement("script");
  script.src = "//unpkg.com/focus-overlay@latest/dist/focusoverlay.js";
  document.head.appendChild(script);
}
</script>

It should be noted that the JavaScript file size of this library is 11.5 KB (4.2 KB after compression) and the CSS file size is 453 B (290 B after compression). This requires consideration of performance impact, as performance and accessibility are interrelated.

Performance does not depend only on script size. This library appends a focal element with a high z-index and pointer-events: none attributes<div> Elements to create focus rings and use absolute positioning and CSS animations to control their position and size. However, frequent modification of <code>top , left , width and height properties of the absolute positioning element may affect performance. It is recommended that future versions can consider using FLIP animation technology to optimize performance and only animation transform attributes.

The above is the detailed content of Animated Position of Focus Ring. For more information, please follow other related articles on the PHP Chinese website!