HTML <ol> id Attribute

The id attribute on an <ol> tag assigns an identifier to the ordered list. The identifier must be unique across the page.

Example

#

An id attribute on an <ol> element.

  1. Amsterdam
  2. London
  3. Berlin
  4. Paris
<ol id="locations">
  <li>Amsterdam</li>
  <li>London</li>
  <li>Berlin</li>
  <li>Paris</li>
</ol>

Using id

The id attribute assigns an identifier to the <ol> element.

The identifier must be unique across the page.

The id allows programmatic access to the <ol> element.

Tip:  id is a global attribute that can be applied to any HTML element.


Syntax

<ol id="identifier" />

Values

#

Value Description
identifier A unique alphanumeric string. The id value must begin with a letter ([A-Za-z]) and may be followed by any number of letters, digits ([0-9]), hyphens (-), underscores (_), colons (:), and periods (.).

More Examples

An <ol> tag with a unique id.
Clicking the button displays the number of items inside the ordered list.

  1. Amsterdam
  2. London
  3. Berlin
  4. Paris

<ol id="myol">
  <li>Amsterdam</li>
  <li>London</li>
  <li>Berlin</li>
  <li>Paris</li>
</ol>

<br/>
<button onclick="show();">Show # cities</button>

<script>
  let show = () => {
    let element = document.getElementById("myol");
    let length = element.getElementsByTagName("li").length;
    alert("# Cities: " + length);
  }
</script>

Code explanation

The id attribute assigns a unique identifier for the <ol>.

Clicking the button calls JavaScript that locates the <ol> through the id.

It then counts the number of <li> tags inside the <ol> and displays it in an alert box.


Browser support

Here is when id support started for each browser:

Chrome
1.0 Sep 2008
Firefox
1.0 Sep 2002
IE/Edge
1.0 Aug 1995
Opera
1.0 Jan 2006
Safari
1.0 Jan 2003

You may also like

 Back to <ol>
Guides