HTML <th> class Attribute

HTML <tfoot>

HTML <thead>

The class attribute assigns one or more classnames to the <th> tag.

Classnames are defined in a stylesheet or in a local <style> element.

Classes, i.e. classnames, are used to style elements.

Example

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A class attribute styling a <th> element.

Customers
Denice	Hobermann
Paulo	Cornell

<style>
  table.tb { width: 250px; border-collapse: collapse; }
  .tb th, .tb td { border: solid 1px #777; padding: 5px; }
  .th-blue { background-color:lightblue; }
</style>

<table class="tb">
  <tr>
    <th class="th-blue" colspan="2">Customers</th>
  </tr>
  <tr>
    <td>Denice</td>
    <td>Hobermann</td>
  </tr>
  <tr>
    <td>Paulo</td>
    <td>Cornell</td>
  </tr>
</table>

Using class

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Classes (i.e. classnames) are used for styling the th element.

Multiple classnames are separated by a space.

JavaScript uses classes to access elements by classname.

Tip: class is a global attribute that can be applied to any HTML element.

Syntax

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<th class="classnames">

Values

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Value	Description
classnames	One or more space-separated class names.

More Examples

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A class attribute styling a <th> element.
Clicking the button toggles a classname that changes the header cell to dark mode.

Customers
Denice	Hobermann
Paulo	Cornell

<style>
  table.tb { width: 250px; border-collapse: collapse; }
  .tb th, .tb td { border: solid 1px #777; padding: 5px; }
  .th-blue { background-color:lightblue; }
  .th-dark { background-color: #222; color: #fff; } 
</style>

<table class="tb">
  <tr>
    <th id="myth" class="th-blue" colspan="2">Customers</th>
  </tr>
  <tr>
    <td>Denice</td>
    <td>Hobermann</td>
  </tr>
  <tr>
    <td>Paulo</td>
    <td>Cornell</td>
  </tr>
</table>

<br />
<button onclick="toggle();">Toggle class</button>

<script>
  let toggle = () => {
     let element = document.getElementById("myth");
     element.classList.toggle("th-dark");
  }
</script>

Code explanation

Two CSS classes are defined in the <style> element.

The class attribute in <th> assigns one classname.

Repeatedly clicking the button toggles another class, changing the <th> background and text color of the table header cell.

Browser support

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Here is when class support started for each browser: