coderef

attr() (content only)Baseline · Widely available

The attr() CSS function, in content property declarations, sets a ::before or ::after pseudo-element's content to the value of the specified HTML attribute.

Supported in all major browsers for at least 30 months — safe to use without fallbacks. Baseline since Jul 29, 2015. Widely available since Jan 29, 2018.

How to use ↓Compare browsers

Browser support

DesktopChrome
1–1Not supported
2+Supportedsince May 21, 2009
Current: 155
Edge
12+Supportedsince Jul 29, 2015
Current: 154
Firefox
1+Supportedsince Nov 9, 2004
Current: 157
Safari
1–3Not supported
3.1+Supportedsince Mar 18, 2008
Current: 27
MobileChrome Android
18+Supportedsince Jun 27, 2012
Current: 155
Firefox Android
4+Supportedsince Mar 29, 2011
Current: 157
Safari iOS
1–1Not supported
2+Supportedsince Jul 11, 2008
Current: 27

How to use

This feature is Baseline widely available — use it freely, no fallback needed.

Example

Full syntax and examples are on MDN: attr.

Feature detection

CSS · check before using
@supports (width: attr(data-size type(<length>))) {
  /* styles that use attr */
}

/* or in JavaScript */
if (CSS.supports("width", "attr(data-size type(<length>))")) {
  // use it
}

Documentation (MDN)

Specification