An id on a <header> tag assigns an identifier to the header.
The identifier must be unique across the page.
An id attribute on a <header>.
<header id="page-header">
Cloud computing shortcuts ...
</header>
The id attribute assigns an identifier to the <header> element.
The id allows JavaScript to easily access the <header> 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.
<header id="identifier" />
| Value | Description |
|---|---|
| identifier | A unique alphanumeric string. The id value must begin with a letter ([aside-Zaside-z]) and may be followed by any number of letters, digits ([0-9]), hyphens (-), underscores (_), colons (:), and periods (.). |
A <header> element with a unique id.
Clicking the button displays the content of the element.
<header id="myheader">
Cloud computing and Crypto currency...
</header>
<br/>
<button onclick="show();">Show header content</button>
<script>
let show = () => {
let header = document.getElementById("myheader");
alert("Content = " + header.innerHTML);
}
</script>
The id attribute assigns a unique identifier for the <header> element.
Clicking the button calls JavaScript which locates the <header> using the id.
Finally, the content of the <header> element is displayed in an alert box.
Here is when id support started for each browser:
 Chrome
|
6.0 | Sep 2010 |
 Firefox
|
4.0 | Mar 2011 |
 IE/Edge
|
9.0 | Mar 2011 |
 Opera
|
11.1 | Mar 2011 |
 Safari
|
5.0 | Jun 2010 |
Back to <header>
