An in-depth exploration of virtual selectors: revealing the principles and usage of commonly used selectors

Revealing the secrets of virtual selectors: analyzing the working principles and usage of commonly used selectors

Introduction:

In front-end development, CSS selectors are Very important part. It can help us locate the HTML elements that need to be manipulated and apply styles to them. Virtual selectors, as a special form of CSS selectors, have more powerful functions and flexibility. This article will reveal how virtual selectors work and how they are commonly used.

1. What is a virtual selector?

Virtual selectors (Pseudo-Selectors) are a special form of CSS selectors, used to perform special filtering or special filtering on elements when they are selected. operate. A virtual selector starts with a colon (:) and represents the selection of a pseudo-class state or other attributes of the element.

The virtual selector is set by adding a pair of colons and the corresponding pseudo-class after the selector. For example, :hover represents the state when the mouse is hovering over the element. Common virtual selectors include:hover, :active, :focus, :first-child, etc.

Virtual selectors select or operate elements by judging the element status or other attributes. By flexibly using virtual selectors, we can achieve more precise style control and interaction effects.

2. The working principle and usage of commonly used virtual selectors

1. :hover

:hover virtual selector is used to select the element when the mouse is hovering status at the time. A mouseover effect can be achieved by adding specific styles to the selected element.

2. :active

:active virtual selector is used to select the state when the mouse clicks the element. By adding a specific style to the selected element, you can achieve the effect when the element is clicked.

3. :focus

:The focus virtual selector is used to select the currently focused element. Generally used for form elements. When the user clicks on the form element, the element gets focus. By adding specific styles to the focused element, you can achieve interactive effects or indicate the user's current location.

4. :first-child

:first-child virtual selector is used to select the first child element under the parent element. By setting :first-child, you can style the first child element individually, for example by setting its font color to be different from other child elements.

5. :nth-child

:nth-child virtual selector is used to select the nth child element under the parent element. By setting :nth-child(n), the child element at a specific position can be selected. For example, setting: nth-child(2n) can select even-numbered child elements under the parent element.

6. ::before and ::after

The::before and ::after virtual selectors are used to insert content before and after the content of an element. By setting ::before and ::after, you can insert specific content, such as icons, backgrounds, etc., before and after the element.

7. :not

: The not virtual selector is used to select elements that do not match the specified selector. By setting:not(selector), you can exclude certain elements and achieve more precise selection.

8. :checked

:checked The virtual selector is used to select the selected (ie checked) form element. By setting: checked, you can switch the style between selected and unselected states.

Summary:

Virtual selectors are a powerful and indispensable part of CSS selectors. They can accurately select and operate elements by judging the element status or other attributes. Common virtual selectors such as :hover, :active, :focus, etc. can achieve various interactive effects and style control. Proper use of virtual selectors can make pages more attractive and operable. In actual development, it is necessary to select an appropriate virtual selector based on actual needs and flexibly use its features to achieve the best user experience and visual effects.

The working principle and usage examples of virtual selectors have been analyzed in this article, hoping to help readers better understand and apply virtual selectors. Through in-depth study and practice, I believe you can flexibly use virtual selectors in front-end development to achieve various cool effects.

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