An id on a <button> tag assigns an identifier to the button.
The identifier must be unique across the page.
An id attribute on a <button>.
<button id="alert-button"
onclick="alert('The request has been approved!');">Approve</button>
The id attribute assigns an identifier to the <button> element.
The id allows JavaScript to easily access the <button> 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.
<button 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 <button> with a unique id.
Clicking the button will display its content.
<button id="mybutton"
onclick="alert('Calculations have started!');">Calculate Revenues</button>
<br />
<button onclick="show();">Show content</button>
<script>
let show = () => {
let element = document.getElementById("mybutton");
alert("Content = " + element.innerHTML);
}
</script>
The id attribute assigns a unique identifier to the button.
Clicking the button calls JavaScript which locates the button using the id.
Finally, the content of the button 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 <button>
