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HTML <thead> id Attribute

An id on a <thead> tag assigns an identifier to the table header.

The identifier must be unique across the page.

Example

#

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>

Using id

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.


Syntax

<thead id="identifier" />

Values

#

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 (.).

More Examples

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>

Code explanation

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.


Browser support

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

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