How to select all child elements recursively using CSS?

CSS (or Cascading Style Sheets) is used in presenting and designing web pages. It is not used alone, rather it is used with HTML or XML for defining the appearance and layout of web pages. CSS helps developers in styling all the HTML elements including headings, paragraphs, text, images, tables, etc. And not only this, but it also specifies how they should be displayed on different screens, in printables, or on other media types. It can also be used for creating responsive web designs for different screen sizes and devices.

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

What is CSS Selector?

CSS selector is a pattern used for selecting and targeting HTML elements to do styling or other manipulations in an HTML element. A selector selects the elements based on the attributes such as class, id, or type. The syntax for using a CSS selector is given below −

Syntax

element > element {
   //CSS styles go here
}

What is a child selector in CSS?

The child selector in CSS is a combinator that is used to select direct child elements of a parent element. It is defined using the ">" symbol. It also targets the elements that are immediate children of a specified parent element.

Syntax

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

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

The child selector is very useful when there is a need to apply styles to specific child elements of a parent element, without affecting their subordinates or nested children. The child selector also provides a more specific way to target elements in the document tree and can help avoid conflicts with other CSS rules that may apply to similar elements.

Selecting all child elements recursively in CSS

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

Syntax

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

The syntax above selects all the child elements of the "main-list" element, including their nested children. You will notice the space between the "main-list" element and the wildcard selector (*) indicates that we want to select all the 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 selects all the child elements of the "main-list" element recursively, except for the "list-not" element −

Example 1: An example demonstrating selecting all child elements

In the below example, we have defined a class .parent > div that applies a style to any <div> element that is an immediate child of an element with a class of "parent". In this case, the only <div> element that matches this criterion is the one with a type of "main-list".

The style specified in the CSS code sets the background color of the matched <div> element to green. So, the background color of the <div> element with class "main-list" will be green. The <li> elements inside the <div> element with class "main-list" will not be affected by this CSS style because they are not direct children of the parent element with class "parent".

However, the two <li> elements that are direct children of the parent element will not be affected either since they are not <div> 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>

Example 2: An example demonstrating selecting all child elements recursively

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

In the given code, the selector is used in conjunction with the "background-color: green" property, which sets the background color of all child elements of the "div" element with a class of "parent" to green, including the nested "li" element and the "li" element inside the "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>

Conclusion

CSS is a language used for styling web pages. One of the most common tasks in CSS is selecting elements. The child selector in CSS selects 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 done using the () operator.

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