counter()

<custom-ident>

A name identifying the counter, which is the same case-sensitive name used for the counter-reset and counter-increment. The 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 simple 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.

HTML

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

CSS

ol {
  counter-reset: listCounter;
}
li {
  counter-increment: listCounter;
}
li::after {
  content: "[" counter(listCounter) "] == ["
               counter(listCounter, upper-roman) "]";
}

Result

HTML

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

CSS

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

Result

• Using CSS Counters
• counter-reset
• counter-set
• counter-increment
• @counter-style
• CSS counters() function