Improve the search and memory speed of CSS selectors

Quickly find and remember commonly used CSS selectors

CSS selectors are a very important part of web development. They allow us to select elements on web pages. Styling and manipulation. In daily development, mastering commonly used CSS selectors is very important for writing efficient CSS code. The following will introduce some commonly used CSS selectors and provide specific code examples to help you quickly find and remember them.

1. Element selector (element selector)
   The element selector is the most common type of CSS selector, which applies styles by selecting the tag name of the element. For example, the following code will set the text color of all paragraphs to red:

p {
  color: red;
}

2. Class selector (class selector)
   The class selector starts with a period (.) and is selected by Specify the class attribute of the element to apply the style. For example, the following code will set the background color of all elements with class "box" to yellow:

.box {
  background-color: yellow;
}

3. id selector (id selector)
   id selector starts with a pound sign (#), apply the style by selecting the element with the specified id attribute. Note that the id selector should be unique within the same page. For example, the following code will set the font of the element with the id "header" to 20px:

#header {
  font-size: 20px;
}

4. Descendant selector (descendant selector)
   The descendant selector selects the Descendant elements to apply styles to. Descendant selectors use spaces to separate elements. For example, the following code will set the paragraph text color inside all div elements to blue:

div p {
  color: blue;
}

5. Child element selector (child selector)
   The child element selector selects a certain The element's direct child elements to apply the style to. Child element selectors use a greater than sign (>) to separate elements. For example, the following code will set the font size of all direct child elements of div elements with class "container" to 18px:

div > .container {
  font-size: 18px;
}

6. adjacent sibling selector (adjacent sibling selector)
   Adjacent sibling selector applies styles by selecting adjacent sibling elements of an element. Adjacent sibling selectors use a plus sign ( ) to separate elements. For example, the following code will set the background color of all adjacent sibling elements to gray:

div + div {
  background-color: gray;
}

7. pseudo-class selector (pseudo-class selector)
   pseudo-class selector uses Used to select elements in a specific state, for example:hover is used to select elements in the mouse hover state. For example, the following code will set the text color when the mouse is hovering over a link to red:

a:hover {
  color: red;
}

8. pseudo-element selector (pseudo-element selector)
   The pseudo-element selector is used Select a specific part of an element, for example::before is used to add content before the element. For example, the following code will add a text block in front of the p element:

p::before {
  content: "前面有一个文本块";
}

The above are some commonly used CSS selectors and corresponding code examples, which are often used in web development. By mastering these selectors, you can write CSS code more flexibly and efficiently. When you encounter a problem that requires styling, you can quickly find and remember these selectors to solve the problem more quickly. I hope this article will be helpful to everyone’s CSS development.

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