Does the Universal Selector Impact Web Page Performance?

Performance Impact of the Universal Selector

Question:

In an effort to optimize the performance of a web page, concerns have been raised regarding the use of the CSS universal selector (*). Would a specific selector like body, h1, p result in better performance compared to the universal selector? Or do they have an identical effect?

Answer:

The universal selector has a negligible performance impact in modern browsers. This misconception stems from its slower performance in the past. However, with recent improvements, provided that slow effects like box-shadow or z-axis rotation are not applied to every element, the performance difference between the universal selector and specific selectors is minimal.

For example, the following CSS rule using the universal selector:

<code class="css">* {
  margin: 0;
  padding: 0;
}</code>

is equivalent to the following specific selector rule:

<code class="css">body, h1, p {
  margin: 0;
  padding: 0;
}</code>

Both rules will apply the same styles to the HTML elements in a document. While the specific selector is more concise, the universal selector provides a more generic approach for applying styles to all elements, which can be useful in certain situations.

Additional Considerations:

It's important to note that performance improvements may not be significant with the optimization techniques mentioned above. However, they can contribute to overall performance optimization when combined with other performance-enhancing measures. As always, it's advisable to consider the specific context and potential bottlenecks when making optimization decisions.

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