Get a deep understanding of the weight and precedence of CSS selector wildcards

In-depth understanding of the weight and priority of CSS selector wildcards

In CSS style sheets, selectors are an important tool for specifying which HTML elements the style applies to . The selector's priority and weight determine which style is applied when multiple rules apply to an HTML element at the same time.

Wildcard selector is a common selector in CSS. It is represented by the "*" symbol, which means it matches all HTML elements. Wildcard selectors are simple but can be very useful in certain situations. However, the weight and priority of wildcard selectors also require an in-depth understanding.

The priority of a CSS selector is a rule used to determine which style will be applied to an HTML element. Priority is like a weight tag, which is calculated according to certain rules to determine which style to apply. When using wildcard selectors, be aware that the wildcard selector has lower priority because it has a low weight.

First, let’s look at some sample code to better understand the priority and weight of wildcard selectors.

/* 通配符选择器 */
* {
  color: blue;
}

/* 类选择器 */
.my-class {
  color: red;
}

/* ID选择器 */
#my-id {
  color: green;
}

In the above code, we define a wildcard selector "*", a class selector ".my-class" and an ID selector "#my-id". Now, let's look at the priority and effect of these selectors when applied to HTML elements.

<div class="my-class" id="my-id">
  This is a test.
</div>

According to the priority rules of CSS selectors, the ID selector has the highest priority, followed by the class selector, and finally the wildcard selector. So, according to the above code, the style applied on the "div" element should be the green color defined in the ID selector.

However, since the wildcard selector has a lower priority, its style can be overridden by a higher priority selector. So, even though we defined the blue style in the wildcard selector, the final style applied to the "div" element is green because the ID selector has higher priority.

Through this example, we can clearly see that the wildcard selector has low weight and priority and is easily overridden by other selectors.

To summarize, the wildcard selector is a simple but useful selector in CSS. However, it is important to understand the weight and precedence of wildcard selectors. When writing CSS, we should avoid overuse of wildcard selectors because they have lower priority and can easily be overridden by other selectors.

I hope that through the analysis of this article, readers can have a deeper understanding of the weight and priority of CSS selector wildcards so that they can be better applied in actual projects.

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