attr()
Note: The attr()
function can be used with any CSS property, but support for properties other than content
is experimental, and support for the type-or-unit parameter is sparse.
The attr()
CSS function is used to retrieve the value of an attribute of the selected element and use it in the stylesheet. It can also be used on pseudo-elements, in which case the value of the attribute on the pseudo-element's originating element is returned.
Try it
Syntax
css
/* Simple usage */
attr(data-count);
attr(title);
/* With type */
attr(src url);
attr(data-count number);
attr(data-width px);
/* With fallback */
attr(data-count number, 0);
attr(src url, "");
attr(data-width px, inherit);
attr(data-something, "default");
Values
attribute-name
-
The name of an attribute on the HTML element referenced in the CSS.
<type-or-unit>
Experimental-
A keyword representing either the type of the attribute's value, or its unit, as in HTML some attributes have implicit units. If the use of
<type-or-unit>
as a value for the given attribute is invalid, theattr()
expression will be invalid too. If omitted, it defaults tostring
. The list of valid values are:string
-
The attribute value is treated as a CSS
<string>
. It is NOT reparsed, and in particular the characters are used as-is instead of CSS escapes being turned into different characters.Default value: an empty string.
color
Experimental-
The attribute value is parsed as a hash (3- or 6-value hash) or a keyword. It must be a valid CSS
<string>
value. Leading and trailing spaces are stripped.Default value:
currentcolor
. url
Experimental-
The attribute value is parsed as a string that is used inside a CSS
url()
function. Relative URL are resolved relatively to the original document, not relatively to the style sheet. Leading and trailing spaces are stripped.Default value: the URL
about:invalid
that points to a non-existent document with a generic error condition. integer
Experimental-
The attribute value is parsed as a CSS
<integer>
. If it is not valid, that is not an integer or out of the range accepted by the CSS property, the default value is used. Leading and trailing spaces are stripped.Default value:
0
, or, if0
is not a valid value for the property, the property's minimum value. number
Experimental-
The attribute value is parsed as a CSS
<number>
. If it is not valid, that is not a number or out of the range accepted by the CSS property, the default value is used. Leading and trailing spaces are stripped.Default value:
0
, or, if0
is not a valid value for the property, the property's minimum value. length
Experimental-
The attribute value is parsed as a CSS
<length>
dimension, that is including the unit (e.g.12.5em
). If it is not valid, that is not a length or out of the range accepted by the CSS property, the default value is used. If the given unit is a relative length,attr()
computes it to an absolute length. Leading and trailing spaces are stripped.Default value:
0
, or, if0
is not a valid value for the property, the property's minimum value. em
,ex
,px
,rem
,vw
,vh
,vmin
,vmax
,mm
,cm
,in
,pt
, orpc
Experimental-
The attribute value is parsed as a CSS
<number>
, that is without the unit (e.g.12.5
), and interpreted as a<length>
with the specified unit. If it is not valid, that is not a number or out of the range accepted by the CSS property, the default value is used. If the given unit is a relative length,attr()
computes it to an absolute length. Leading and trailing spaces are stripped.Default value:
0
, or, if0
is not a valid value for the property, the property's minimum value. angle
Experimental-
The attribute value is parsed as a CSS
<angle>
dimension, that is including the unit (e.g.30.5deg
). If it is not valid, that is not an angle or out of the range accepted by the CSS property, the default value is used. Leading and trailing spaces are stripped.Default value:
0deg
, or, if0deg
is not a valid value for the property, the property's minimum value. deg
,grad
,rad
Experimental-
The attribute value is parsed as a CSS
<number>
, that is without the unit (e.g.12.5
), and interpreted as an<angle>
with the specified unit. If it is not valid, that is not a number or out of the range accepted by the CSS property, the default value is used. Leading and trailing spaces are stripped.Default value:
0deg
, or, if0deg
is not a valid value for the property, the property's minimum value. time
Experimental-
The attribute value is parsed as a CSS
<time>
dimension, that is including the unit (e.g.30.5ms
). If it is not valid, that is not a time or out of the range accepted by the CSS property, the default value is used. Leading and trailing spaces are stripped.Default value:
0s
, or, if0s
is not a valid value for the property, the property's minimum value. s
,ms
Experimental-
The attribute value is parsed as a CSS
<number>
, that is without the unit (e.g.12.5
), and interpreted as an<time>
with the specified unit. If it is not valid, that is not a number or out of the range accepted by the CSS property, the default value is used. Leading and trailing spaces are stripped.Default value:
0s
, or, if0s
is not a valid value for the property, the property's minimum value. frequency
Experimental-
The attribute value is parsed as a CSS
<frequency>
dimension, that is including the unit (e.g.30.5kHz
). If it is not valid, that is not a frequency or out of the range accepted by the CSS property, the default value is used.Default value:
0Hz
, or, if0Hz
is not a valid value for the property, the property's minimum value. Hz
,kHz
Experimental-
The attribute value is parsed as a CSS
<number>
, that is without the unit (e.g.12.5
), and interpreted as a<frequency>
with the specified unit. If it is not valid, that is not a number or out of the range accepted by the CSS property, the default value is used. Leading and trailing spaces are stripped.Default value:
0Hz
, or, if0Hz
is not a valid value for the property, the property's minimum value. %
Experimental-
The attribute value is parsed as a CSS
<number>
, that is without the unit (e.g.12.5
), and interpreted as a<percentage>
. If it is not valid, that is not a number or out of the range accepted by the CSS property, the default value is used. If the given value is used as a length,attr()
computes it to an absolute length. Leading and trailing spaces are stripped.Default value:
0%
, or, if0%
is not a valid value for the property, the property's minimum value.
<fallback>
Experimental-
The value to be used if the associated attribute is missing or contains an invalid value. If not set, CSS will use the default value defined for each
<type-or-unit>
.
Formal syntax
Examples
content property
HTML
html
<p data-foo="hello">world</p>
CSS
css
[data-foo]::before {
content: attr(data-foo) " ";
}
Result
color value
Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.
HTML
html
<div class="background" data-background="lime">
background expected to be red if your browser does not support advanced usage
of attr()
</div>
CSS
css
.background {
background-color: red;
}
.background[data-background] {
background-color: attr(data-background color, red);
}
Result
Specifications
Specification |
---|
CSS Values and Units Module Level 5 # attr-notation |
Browser compatibility
BCD tables only load in the browser