An id on a <thead> tag assigns an identifier to the table header.
The identifier must be unique across the page.
An id attribute on a <thead> element.
First name | Last name |
---|---|
Denice | Hobermann |
Paulo | Cornell |
Number of rows: 2 |
<style>
table.tb { width:300px; border-collapse: collapse; }
.tb th, .tb td { border: solid 1px #777; padding: 5px; }
.tb thead { background-color:lightblue; }
</style>
<table class="tb">
<thead id="table-header">
<tr>
<th>First name</th>
<th>Last name</th>
</tr>
</thead>
<tbody>
<tr>
<td>Denice</td>
<td>Hobermann</td>
</tr>
<tr>
<td>Paulo</td>
<td>Cornell</td>
</tr>
</tbody>
<tfoot>
<tr>
<td colspan="2">Number of rows: 2</td>
</tr>
</tfoot>
</table>
The id attribute assigns an identifier to the <thead> element.
The id allows JavaScript to easily access the <thead> 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.
<thead 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 <thead> element with a unique id attribute.
Clicking the button displays the total number of cells in the table header.
Customer Name | |
---|---|
First name | Last name |
Denice | Hobermann |
Paulo | Cornell |
Number of rows: 2 |
<style>
table.tbl { width:300px; border-collapse: collapse; }
.tbl th, .tbl td { border: solid 1px #777; padding: 5px; }
.tbl thead { background-color:lightblue; }
</style>
<table class="tb">
<thead id="mythead">
<tr>
<th colspan="2">Customer Name</th>
</tr>
<tr>
<th>First name</th>
<th>Last name</th>
</tr>
</thead>
<tbody>
<tr>
<td>Denice</td>
<td>Hobermann</td>
</tr>
<tr>
<td>Paulo</td>
<td>Cornell</td>
</tr>
</tbody>
<tfoot>
<tr>
<td colspan="2">Number of rows: 2</td>
</tr>
</tfoot>
</table>
<br />
<button onclick="show();">Show # thead cells</button>
<script>
let show = () => {
let element = document.getElementById("mythead");
let length = element.getElementsByTagName("th").length;
alert("# Cells = " + length);
}
</script>
The id attribute assigns a unique identifier for the <thead>.
Clicking the button calls JavaScript which locates the <thead> using the id.
It then counts the number of <th> inside the <thead> 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 <thead>