What are the style selectors?

Style selectors include element selector, class selector, ID selector, attribute selector, descendant selector, child element selector, adjacent sibling selector, universal sibling selector, and pseudo-class selector and pseudo-element selectors, etc. Detailed introduction: 1. Element selector, selects elements through the tag name of HTML elements; 2. Class selector, selects elements through the class attribute of the element, and uses the "." symbol to represent the class selector; 3. ID selector, through The id attribute of the element selects the element, and the "#" symbol is used to represent the ID selector; 4. Attribute selector, etc.

The operating system for this tutorial: Windows 10 system, DELL G3 computer.

In CSS, style selectors are used to select HTML elements to which styles need to be applied. CSS provides a variety of style selectors. The following are some commonly used style selectors:

1. Element Selector (Element Selector): Select elements through the tag names of HTML elements. For example, the p selector selects all paragraph elements.

2. Class Selector: Select elements through their class attributes. Use the "." symbol to represent class selectors. For example, .red will select elements with the class attribute "red".

3. ID Selector: Select elements through their id attribute. Use the "#" symbol to represent ID selectors. For example, #header selects elements with the id attribute "header".

4. Attribute Selector: Select elements through their attributes. For example, [type="text"] will select all elements whose type attribute value is "text".

5. Descendant Selector: Select elements through their descendant relationship. Use spaces to indicate descendant selectors. For example, div p will select all paragraph elements inside the div element.

6. Child Selector: Select elements through their direct child element relationship. Use the ">" symbol to represent child element selectors. For example, ul > li will select the direct child element li under the ul element.

7. Adjacent Sibling Selector: Selects the sibling element immediately following the specified element. Use the " " notation to represent adjacent sibling selectors. For example, h1 p will select the paragraph element immediately following the h1 element.

8. General Sibling Selector: Selects all sibling elements that have the same parent element as the specified element and are behind the specified element. Use the "~" symbol to represent a universal sibling selector. For example, h1 ~ p will select all paragraph elements that have the same parent element as the h1 element and are behind the h1 element.

9. Pseudo-class Selector: Select elements through their special status. Pseudo-class selectors start with ":". For example, a:hover selects the mouse-over state of a link.

10. Pseudo-element Selector: Select a specific part of the element. Pseudo-element selectors start with "::". For example, ::before selects content inserted before the element.

In addition to the common style selectors listed above, there are some other style selectors, such as parent element selectors, space selectors, etc. Different style selectors can be combined for more precise element selection and style application.

It should be noted that the more specific the selection range of the style selector, the higher the priority. When writing CSS styles, you should choose the appropriate style selector according to specific needs to ensure that the style can be accurately applied to the target element. At the same time, you should also pay attention to the performance of the style selector to avoid rendering performance degradation caused by overly complex selectors.

To summarize, CSS provides a variety of style selectors, including element selectors, class selectors, ID selectors, attribute selectors, descendant selectors, child element selectors, adjacent sibling selectors, Universal sibling selector, pseudo-class selector, pseudo-element selector, etc. By rationally using these style selectors, you can accurately select elements and apply styles to achieve rich and diverse page layouts and effects.

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