An in-depth analysis of the application skills of CSS advanced selectors

In-depth discussion of how to use CSS advanced selectors requires specific code examples

CSS, as a style sheet language, can not only beautify the appearance of web pages, but also It allows us to better control and select web page elements. In CSS, in addition to basic selectors (such as element selectors, class selectors, and ID selectors), there are also some advanced selectors that can select specific elements based on more complex conditions. This article will delve into the use of CSS advanced selectors and provide specific code examples.

1. Child selector (child selector)

The child selector can select the direct child elements of the specified element. The syntax is "parent > child", where parent is the selector of the parent element and child is the selector of the child element.

For example, if we want to select the direct child element p under all div elements, we can use the following code:

div > p {
  color: red;
}

2. Adjacent sibling selector (adjacent sibling selector)

The adjacent sibling selector can select the sibling elements immediately behind the specified element. The syntax is "element sibling", where element is the selector for the specified element and sibling is the selector for sibling elements.

For example, if we want to select the first p element immediately after the h1 element, we can use the following code:

h1 + p {
  color: blue;
}

3. General sibling selector (general sibling selector)

The universal sibling selector can select all sibling elements after the specified element. The syntax is "element ~ sibling", where element is the selector of the specified element and sibling is the selector of the sibling element.

For example, if we want to select all p elements after the h2 element, we can use the following code:

h2 ~ p {
  font-size: 16px;
}

4. Attribute selector

Attribute selector can select elements with specified attributes. Its syntax has many forms:

• [attribute]: selects all elements with the specified attribute;
• [attribute=value]: selects elements whose attribute value is the specified value;
• [attribute~=value]: Select elements whose attribute value contains the specified value;
• [attribute|=value]: Select elements whose attribute value is the specified value or starts with the specified value;
• [attribute^=value]: Select elements whose attribute value starts with the specified value;
• [attribute$=value]: Select elements whose attribute value ends with the specified value;
• [attribute*=value]: Select elements whose attribute value contains the specified value.

For example, if we want to select all a elements with class attributes, we can use the following code:

a[class] {
  text-decoration: underline;
}

5. pseudo-class selector

Pseudo-class selectors can select elements in a specific state. Some of the commonly used pseudo-class selectors are:

• :hover: selects the state when the mouse is hovering over the element;
• :active: selects the element that is being clicked by the user;
• :visited: Select the visited link element;
• :first-child: Select the first child element of the parent element.

For example, if we want to select all button elements that are hovered by the mouse, we can use the following code:

button:hover {
  background-color: yellow;
}

6. pseudo-element selector(pseudo-element selector)

Pseudo-element selectors can select specific parts of an element, such as the first letter of the element or the content after the content. Some commonly used pseudo-element selectors are:

• ::first-letter: selects the first letter of the element;
• ::first-line: selects the first letter of the element Line;
• ::before: Add content before the element content;
• ::after: Add content after the element content.

For example, if we want to set a special style for the first letter of a paragraph, we can use the following code:

p::first-letter {
  font-size: 24px;
  font-weight: bold;
  color: red;
}

The above introduces several commonly used CSS advanced selectors and their use Method, by rationally using these selectors, we can control and select web page elements more flexibly and achieve cooler effects. However, you should also pay attention to the compatibility and performance issues of the selector during use to avoid affecting the loading speed and user experience of the web page. I hope this article can be helpful to everyone when using CSS advanced selectors!

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