counter() CSS function

The counter() CSS function returns a string representing the current value of the named counter, if there is one.

The counter() function is generally used within pseudo-element through the content property but, theoretically, it can be used wherever a <string> value is supported.

Try it

.double-list {
  counter-reset: count -1;
}

.double-list li {
  counter-increment: count 2;
}

.double-list li::marker {
  content: counter(count, decimal) ") ";
}
<p>Best Dynamic Duos in Sports:</p>
<ol class="double-list">
  <li>Simone Biles + Jonathan Owens</li>
  <li>Serena Williams + Venus Williams</li>
  <li>Aaron Judge + Giancarlo Stanton</li>
  <li>LeBron James + Dwyane Wade</li>
  <li>Xavi Hernandez + Andres Iniesta</li>
</ol>

Syntax

css
/* Basic usage */
counter(counter-name);

/* changing the counter display */
counter(counter-name, upper-roman)

Counters have no visible effect by themselves. The counter() and counters() functions are what make counters useful by returning developer-defined strings (or images).

Values

The counter() function accepts up to two parameters. The first parameter is the <counter-name>. The optional second parameter is the <counter-style>.

<counter-name>

A <custom-ident> identifying the counter, which is the same case-sensitive name used with the counter-reset and counter-increment property values. The counter name cannot start with two dashes and can't be none, unset, initial, or inherit.

<counter-style>

A list-style-type name, counter-style-name or symbols() function, where a counter style name is a numeric, alphabetic, or symbolic predefined counter style, a complex longhand east Asian or Ethiopic predefined counter style, or other predefined counter style. If omitted, the counter-style defaults to decimal.

Note: To join the counter values when nesting counters, use the counters() function, which provides an additional <string> parameter.

Formal syntax

<counter()> = 
  counter( <counter-name> , <counter-style>? )  

<counter-name> = 
  <custom-ident>  

<counter-style> = 
  <counter-style-name>  |
  <symbols()>           

<counter-style-name> = 
  <custom-ident>  

<symbols()> = 
  symbols( <symbols-type>? [ <string> | <image> ]+ )  

<symbols-type> = 
  cyclic      |
  numeric     |
  alphabetic  |
  symbolic    |
  fixed       

<image> = 
  <url>           |
  <image()>       |
  <image-set()>   |
  <cross-fade()>  |
  <element()>     |
  <gradient>      

<image()> = 
  image( <image-tags>? [ <image-src>? , <color>? ]! )  

<image-set()> = 
  image-set( <image-set-option># )  

<cross-fade()> = 
  cross-fade( <cf-image># )  

<element()> = 
  element( <id-selector> )  

<image-tags> = 
  ltr  |
  rtl  

<image-src> = 
  <url>     |
  <string>  

<image-set-option> = 
  [ <image> | <string> ] [ <resolution> || type( <string> ) ]?  

<cf-image> = 
  [ <image> | <color> ]  &&
  <percentage [0,100]>?  

<id-selector> = 
  <hash-token>

Examples

undefined

lower-roman compared to lower-alpha

In this example, we display a counter using lower-roman and lower-alpha list styles.

HTML

html
<ol>
  <li></li>
  <li></li>
  <li></li>
</ol>

CSS

css
ol {
  counter-reset: count;
}
li {
  counter-increment: count;
}
li::after {
  content:
    "[" counter(count, lower-roman) "] == ["
    counter(count, lower-alpha) "]";
}

Result

Displaying a counter using three styles

In this example, we use the counter() function three times.

HTML

html
<ol>
  <li></li>
  <li></li>
  <li></li>
</ol>

CSS

We include the counter() function with three different counter styles, including the default decimal value. We've added padding to the list to provide space for the long ::marker string.

css
ol {
  counter-reset: listCounter;
  padding-left: 5em;
}
li {
  counter-increment: listCounter;
}
li::marker {
  content:
    "Item #" counter(listCounter) " is: ";
}
li::after {
  content:
    "[" counter(listCounter, decimal-leading-zero) "] == ["
    counter(listCounter, upper-roman) "]";
}

Result

Specifications

See also