HTML <main> id Attribute

The id attribute on a <main> tag assigns an identifier to the main section element. The identifier must be unique across the page.

Example

#

An id attribute on a <main> element.

Impressionism is a 19th-century art movement characterized by relatively small brush strokes, emphasis on accurate depiction of light, ordinary subject matter, and unusual visual angles. Impressionism originated with a group of Paris-based artists whose independent exhibitions brought them to prominence in the 1870s and 1880s.
<main id="impressionism">
  <b>Impressionism</b> is a 19th-century art movement 
  characterized by relatively small brush strokes, 
  emphasis on accurate depiction of light, ordinary
  subject  matter, and unusual visual angles. 
  Impressionism originated  with a group of 
  Paris-based artists whose independent exhibitions 
  brought them to prominence in the 1870s and 1880s.
</main>

Using id

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

The identifier must be unique across the page.

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

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


Syntax

<main 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

A <main> element with a unique id.
Clicking the button will display a character count for the text in the element.

Impressionism is a 19th-century art movement characterized by relatively small brush strokes, emphasis on accurate depiction of light, ordinary subject matter, and unusual visual angles. Impressionism originated with a group of Paris-based artists whose independent exhibitions brought them to prominence in the 1870s and 1880s.

<main id="mymain">
  <b>Impressionism</b> is a 19th-century art movement 
  characterized by relatively small brush strokes, 
  emphasis on accurate depiction of light, ordinary
  subject  matter, and unusual visual angles. 
  Impressionism originated  with a group of 
  Paris-based artists whose independent exhibitions 
  brought them to prominence in the 1870s and 1880s.
</main>

<br />
<button onclick="show();">Show character count</button>

<script>
  let show = () => {
    let content = document.getElementById("mymain").innerHTML;
    let count = content.length;
    alert("Count = " + count);
  }
</script>

Code explanation

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

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

It then counts the number of characters in the <main> content and displays it in an alert box.


Browser support

Here is when id support started for each browser:

Chrome
6.0 Sep 2010
Firefox
4.0 Mar 2011
IE/Edge
12.0 Jul 2015
Opera
11.1 Mar 2011
Safari
5.0 Jun 2010

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