An id on an <ol> tag assigns an identifier to the element.
The identifier must be unique across the page.
An id attribute on an <ol> element.
<ol id="locations">
<li>Amsterdam</li>
<li>London</li>
<li>Berlin</li>
<li>Paris</li>
</ol>
The id attribute assigns an identifier to the <ol> element.
The id allows JavaScript to easily access the <ol> 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.
<ol 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 (.). |
An <ol> tag with a unique id.
Clicking the button displays the number of items inside the ordered list.
<ol id="myol">
<li>Amsterdam</li>
<li>London</li>
<li>Berlin</li>
<li>Paris</li>
</ol>
<br/>
<button onclick="show();">Show # cities</button>
<script>
let show = () => {
let element = document.getElementById("myol");
let length = element.getElementsByTagName("li").length;
alert("# Cities: " + length);
}
</script>
The id attribute assigns a unique identifier for the <ol>.
Clicking the button calls JavaScript that locates the <ol> through the id.
It then counts the number of <li> tags inside the <ol> and displays it 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 <ol>