An id on a <nav> tag assigns an identifier to the element.
The identifier must be unique across the page.
An id attribute on a <nav> element.
<nav id="nav-chapters">
<a href="javascript:alert('Going to Introduction')">Introduction</a> <br />
<a href="javascript:alert('Going to What Is HTML')">What is HTML</a> <br />
<a href="javascript:alert('Going to HTML Syntax')">HTML Syntax</a> <br />
<a href="javascript:alert('Going to HTML Elements')">HTML Elements</a>
</nav>
The id attribute assigns an identifier to the <nav> element.
The id allows JavaScript to easily access the <nav> 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.
<nav 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 (.). |
A <nav> element with a unique id.
Clicking the button will display the number of links inside the navigation element.
<nav id="mynav">
<a href="javascript:alert('Going to Introduction')">Introduction</a> <br />
<a href="javascript:alert('Going to What Is HTML')">What is HTML</a> <br />
<a href="javascript:alert('Going to HTML Syntax')">HTML Syntax</a> <br />
<a href="javascript:alert('Going to HTML Elements')">HTML Elements</a>
</nav>
<br/>
<button onclick="show();">Show # links</button>
<script>
let show = () => {
let element = document.getElementById("mynav");
let length = element.getElementsByTagName("a").length;
alert("Link count = " + length);
}
</script>
The id attribute assigns a unique identifier for the <nav>.
Clicking the button calls JavaScript which locates the <nav> using the id.
It then counts the number of <a> tags inside the <nav> and displays it 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
|
11.0 | Dec 2010 |
 Safari
|
5.0 | Jun 2010 |
Back to <nav>
