How to recursively select all child elements using CSS?-CSS Tutorial-php.cn

How to recursively select all child elements using CSS?

CSS (or Cascading Style Sheets) is used to render and design web pages. It is not used alone, but rather together with HTML or XML to define the appearance and layout of a web page. CSS helps developers style all HTML elements, including headings, paragraphs, text, images, tables, and more. Not only that, it also specifies how they display on different screens, printable or other media types. It can also be used to create responsive web designs for different screen sizes and devices.

CSS plays an important role in web development as it is widely supported by all major web browsers, enabling developers to create excellent user interfaces (UI) and dynamic web applications that engage users and enhance their overall experience. Selecting elements is one of the most common tasks when styling HTML elements using CSS. You'll notice that in some cases we may want to select all child elements of an element, including their nested children. In this article, we will see how to select all these child elements recursively with the help of CSS.

What are CSS selectors?

CSS selectors are a pattern for selecting and positioning HTML elements for styling or other operations. Selectors select elements based on attributes such as class, id, or type. The syntax for using CSS selectors is as follows:

grammar

element > element {
   //CSS styles go here
}

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What is a child selector in CSS?

The child selector in CSS is a combinator that selects direct child elements of the parent element. It is defined using the ">" symbol. It also selects direct child elements of the specified parent element.

grammar

.parent > li {
   //CSS styles go here
}

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The syntax consists of the ">" symbol, which only targets direct child elements of the "main-list" element, in this case "li". Therefore, the CSS rule defined above only selects the "List Item 1" and "List Item 2" lists, but not the "List 1" list nested within a nested ul element.

Child selectors are useful when you need to apply styles to specific child elements of a parent element without affecting their subordinate or nested child elements. Child selectors also provide a more specific way to locate elements in the document tree and can help avoid conflicts with other CSS rules that may apply to similar elements.

Recursively select all child elements in CSS

Sometimes there may be a situation where we need to select all child elements, we can use CSS selectors to select elements using the (*) operator. The syntax for selecting all child elements of an element is defined using the ">" operator. For example, the following CSS rule selects all direct children of the "parent" element.

grammar

.main-list > * {
   //CSS styles go here
}

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The above syntax selects all child elements of the "main-list" element, including their nested child elements. You'll notice that the space between the "main-list" element and the wildcard selector (*) indicates that we want to select all descendants of the "parent" element, not just the direct children.

You can also use the " :not() " pseudo-class to exclude certain elements from the selection. For example, the following CSS rule recursively selects all child elements of the "main-list" element, except the "list-not" element -

Example 1: Example demonstrating selecting all child elements

In the example below, we define a .parent > div class that applies styles to any element that is a direct child of an element with the "parent" class. In this case, the only element that meets this condition is the element of type "main-list".

The style specified in the CSS code sets the background color of the matching

element to green. Therefore, the background color of the

element with the class name "main-list" will be green. The

elements inside the

element with class name "main-list" will not be affected by this CSS style because they are not direct children of the parent element with class name "parent".

However, the two

elements that are direct children of the parent element will also not be affected because they are not elements.

<!DOCTYPE html>
<html>
   <head>
      <style>
         .parent > div {
            background-color: green;
         }
      </style>
   </head>
   <body>
      <div class="parent">
         <div class="main-list">
            <li>List item 1</li>
            <li>List item 2</li>
         </div>
         <li>List item 3</li>
         <li>List item 4</li>
      </div>
   </body>
</html>

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Example 2: Example demonstrating recursive selection of all child elements

In the given example, the CSS selector "div.parent > *" is used to recursively select all the child elements of the "div" element that have the "parent" class, which means it selects all the descendants of "div" " elements, including nested elements.

In the given code, the selector is used in conjunction with the "background-color: green" attribute, which sets the background color to green for all child elements of the "div" element with class "parent", including insets. Set of "li" elements and "li" elements within a "span" element.

<!DOCTYPE html>
<html>
   <head>
      <style>
         div.parent,
         div.parent > * {
            background-color: green;
         }
      </style>
   </head>
   <body>
      <div class="parent">
         <li>List item 1</li>
         <li>List item 2</li>
         <span>
            <li>List item 3</li>
         </span>
      </div>
      <li>List item 4</li>
      <li>List item 5</li>
   </body>
</html>

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in conclusion

CSS is a language used to style web pages. In CSS, selecting elements is one of the most common tasks. Child selectors in CSS are used to select direct child elements of a parent element. It is defined using the ">" symbol. Sometimes we need to select all child elements recursively, which can be achieved using the () operator.

By using a space between the parent element and the wildcard selector (), we can select all descendant elements of the parent element. The ":not()" pseudo-class can also be used to exclude certain elements from the selection. CSS selectors are essential for creating visually appealing and dynamic websites that enhance user experience.

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source：tutorialspoint.com

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