An id on a <h1>-<h6> tag assigns an identifier to the heading.
The identifier must be unique across the page.
An id attribute on an <h3> element.
In 1980, physicist Tim Berners-Lee, a contractor at CERN, proposed and prototyped ENQUIRE, a system for CERN researchers to use and share documents. In 1989, Berners-Lee wrote a memo proposing an Internet-based hypertext system. Berners-Lee specified HTML and wrote the browser and server software in late 1990.
<article>
<h3 id="article-heading">The Origins of HTML</h3>
<p>
In 1980, physicist Tim Berners-Lee, a contractor at
CERN, proposed and prototyped ENQUIRE, a system for
CERN researchers to use and share documents. In 1989,
Berners-Lee wrote a memo proposing an Internet-based
hypertext system. Berners-Lee specified HTML and wrote
the browser and server software in late 1990.
</p>
</article>
The id attribute assigns an identifier to the <h1> to <h6> elements.
The id allows JavaScript to easily access the <h1> to <h6> elements.
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.
<h1 | h2 | h3 | h4 | h5 | h6 id="identifier" />
| Value | Description |
|---|---|
| identifier | A unique alphanumeric string. The id value must begin with a letter ([article-Zarticle-z]) and may be followed by any number of letters, digits ([0-9]), hyphens (-), underscores (_), colons (:), and periods (.). |
A <h3> element with a unique id.
Clicking the button displays the heading text.
The California Gold Rush (1848–1855) was a gold rush that began on January 24, 1848, when gold was found by James W. Marshall at Sutter's Mill in Coloma, California. The news of gold brought approximately 300,000 people to California from the rest of the United States and abroad.
<article>
<h3 id="myheading">The California Gold Rush</h3>
<p>
The California Gold Rush (1848–1855) was a gold
rush that began on January 24, 1848, when gold was
found by James W. Marshall at Sutter's Mill in Coloma,
California. The news of gold brought approximately
300,000 people to California from the rest of the
United States and abroad.
</p>
</article>
<br/>
<button onclick="show();">Show heading</button>
<script>
let show = () => {
let element = document.getElementById("myheading");
alert("Heading = " + element.innerHTML);
}
</script>
The id attribute assigns a unique identifier for the <h3> element.
Clicking the button calls JavaScript which locates the <h3> using the id.
Finally, the content of the <h3> element is displayed in an alert box.
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 |
Back to <h1 to h6>
