HTML <var> id Attribute

An id on a <var> tag assigns an identifier to the element.

The identifier must be unique across the page.



An id attribute on a <var> tag.

πr^2 is the area of a circle.

  &pi;<var id="radius">r</var>^2 is the area of a circle.

Using id

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

The id allows JavaScript to easily access the <var> element.

It is also used to point to a specific id selector in a style sheet.

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


<var id="identifier"/>



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

A <var> element with a unique id.
Clicking the button displays the text of the variable element.

πr^2 is the area of a circle.

<p>&pi;<var id="mayvar">r</var>^2 is the area of a circle. </p>
<br />
<button onclick="show();">Show variable</button>

  let show = () => {
     let element = document.getElementById("mayvar");
     alert("Variable = " + element.innerHTML);

Code explanation

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

Clicking the button calls JavaScript which locates the <var> using the id.

Finally, the content of the <var> element is displayed in an alert box.

Browser support

Here is when id support started for each browser:

1.0 Sep 2008
1.0 Sep 2002
1.0 Aug 1995
1.0 Jan 2006
1.0 Jan 2003

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Last updated on Sep 30, 2023