:empty - CSS: Cascading Style Sheets 编辑

The :empty CSS pseudo-class represents any element that has no children. Children can be either element nodes or text (including whitespace). Comments, processing instructions, and CSS content do not affect whether an element is considered empty.

Note: In Selectors Level 4 the :empty pseudo-class was changed to act like :-moz-only-whitespace, but no browser currently supports this yet.

/* Selects any <div> that contains no content */
div:empty {
  background: lime;
}

Syntax

:empty

Examples

HTML

<div class="box"><!-- I will be lime. --></div>
<div class="box">I will be pink.</div>
<div class="box">
	<!-- I will be pink in older browsers because of the whitespace around this comment. -->
</div>
<div class="box">
	<p><!-- I will be pink in all browsers because of the non-collapsible whitespace and elements around this comment. --></p>
</div>

CSS

body {
  display: flex;
  justify-content: space-around;
}

.box {
  background: pink;
  height: 80px;
  width: 80px;
}

.box:empty {
  background: lime;
}

Result

Accessibility concerns

Assistive technology such as screen readers cannot parse interactive content that is empty. All interactive content must have an accessible name, which is created by providing a text value for the interactive control's parent element (anchors, buttons, etc.). Accessible names expose the interactive control to the accessibility tree, an API that communicates information useful for assistive technologies.

The text that provides the interactive control's accessible name can be hidden using a combination of properties that remove it visually from the screen but keep it parseable by assistive technology. This is commonly used for buttons that rely solely on an icon to convey purpose.

• What is an accessible name? | The Paciello Group
• Hidden content for better a11y | Go Make Things
• MDN Understanding WCAG, Guideline 2.4 explanations
• Understanding Success Criterion 2.4.4 | W3C Understanding WCAG 2.0

Specifications

Browser compatibility

BCD tables only load in the browser

See also

• :-moz-only-whitespace  – The prefixed implementation of the changes in Selectors Level 4
• :blank