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HTML: col tag

HTML: <col> tag

In this series of learning HTML, we will teach you how to use the HTML col tag with proper syntax and lots of examples. Let’s start on the HTML col tag.

Description of HTML col tag

The HTML <col> tag defines a column within an HTML table. It is used to apply styles to a specific column or group of columns within a table.

The <col> tag is typically used within the <colgroup> element, which is used to group several <col> tags together. This allows you to apply styles to multiple columns at once. Here is an example:

<table>
<colgroup>
<col style="background-color: red;">
<col>
<col>
</colgroup>
<tr>
<td>Column 1</td>
<td>Column 2</td>
<td>Column 3</td>
</tr>
<tr>
<td>1</td>
<td>2</td>
<td>3</td>
</tr>
<tr>
<td>4</td>
<td>5</td>
<td>6</td>
</tr>
</table>

In this example, the <colgroup> element groups three <col> tags together. The first <col> tag has a style attribute that sets the background color to red. This style will apply to the first column in the table.

Note that the <col> tag does not actually contain any content. It is used solely for styling purposes.

 

Syntax of HTML col tag

The HTML col tag is used to define properties for one or more columns in a table. The syntax of the col tag is as follows:



<table>
<colgroup>
<col>
<col>
...
</colgroup>
<thead>
<tr>
<th>Header 1</th>
<th>Header 2</th>
...
</tr>
</thead>
<tbody>
<tr>
<td>Data 1</td>
<td>Data 2</td>
...
</tr>
...
</tbody>
</table>

Here, the colgroup tag encloses one or more col tags that define the properties of one or more columns in the table. The thead tag and tbody tag contain the headers and data rows respectively.

The col tag can have several attributes that can be used to define its properties. For example:

  • span: This attribute specifies the number of columns the col element should span. By default, it spans one column.
  • style: This attribute can be used to apply CSS styles to the column.

Example:

<table>
<colgroup>
<col style="background-color: #eee;">
<col span="2">
...
</colgroup>
<thead>
<tr>
<th>Header 1</th>
<th>Header 2</th>
<th>Header 3</th>
...
</tr>
</thead>
<tbody>
<tr>
<td>Data 1</td>
<td>Data 2</td>
<td>Data 3</td>
...
</tr>
...
</tbody>
</table>

This will create a table with a light gray background color for the first column, and the second and third columns spanning two columns each.

 

Global Attributes

Actually, there is no HTML tag named “col” that has global attributes. However, there is a “col” tag in HTML tables that has specific attributes.

The “col” tag is used to define a column within an HTML table, and it can have the following attributes:

  • span: specifies the number of columns the <col> element should span
  • style: specifies an inline CSS style for the <col> element
  • class: specifies one or more class names for the <col> element, which can be used to apply CSS styles to multiple <col> elements at once.

Here is an example of how the “col” tag can be used in an HTML table:

<table>
<colgroup>
<col style="background-color: red;">
<col span="2" class="wide-col">
</colgroup>
<tr>
<td>Row 1, Column 1</td>
<td>Row 1, Column 2</td>
<td>Row 1, Column 3</td>
</tr>
<tr>
<td>Row 2, Column 1</td>
<td>Row 2, Column 2</td>
<td>Row 2, Column 3</td>
</tr>
</table>

In this example, the first <col> element has an inline style that sets its background color to red, and the second <col> element has a “span” attribute of 2, which means it should span two columns. Additionally, the second <col> element has a “class” attribute of “wide-col”, which could be used in CSS to apply styles to all <col> elements with that class.

Event Attributes

There are no specific event attributes for the “col” tag in HTML tables. However, events can be attached to the table cells (<td>) within a specific column.

For example, you can use the “onclick” event to trigger a function when a user clicks on a cell within a particular column:

<table>
<colgroup>
<col>
<col>
<col onclick="myFunction()">
</colgroup>
<tr>
<td>Row 1, Column 1</td>
<td>Row 1, Column 2</td>
<td>Row 1, Column 3</td>
</tr>
<tr>
<td>Row 2, Column 1</td>
<td>Row 2, Column 2</td>
<td>Row 2, Column 3</td>
</tr>
</table>

<script>
function myFunction() {
alert("You clicked on a cell in column 3!");
}
</script>

In this example, the third <col> element has an “onclick” attribute that triggers the “myFunction()” function when the user clicks on any cell in that column. The function displays an alert message to let the user know that they clicked on a cell in column 3.

You can also use other event attributes like “onmouseover” or “onmouseout” to trigger functions when the user hovers over or moves the mouse away from a cell in a particular column.

 

Other Attributes

There are no attributes other than global attributes and event attributes for the “col” tag in HTML tables.

Global attributes apply to all HTML tags and provide common features like “id”, “class”, “style”, and “title”. These attributes can be used with any HTML tag, including the “col” tag.

Event attributes allow you to trigger functions based on user actions, such as clicking or hovering over an element. These attributes can also be used with any HTML tag, including the “col” tag, as I explained in my previous answer.

However, there are some other attributes that apply specifically to the “col” tag, but they are not related to the functionality or behavior of the tag. These attributes are used to define the visual appearance of the column.

The following attributes are specific to the “col” tag:

  • width: specifies the width of the column in pixels or as a percentage of the table width
  • align: specifies the horizontal alignment of the column content (left, center, right)
  • valign: specifies the vertical alignment of the column content (top, middle, bottom)
  • char: specifies a character to align the content of the column around
  • charoff: specifies the number of pixels to offset the alignment character.

Note that these attributes are not recommended for use in modern HTML development because they mix presentation with content. It is generally recommended to use CSS styles instead of HTML attributes for defining the visual appearance of elements.

Notes on HTML: col tag

Here are some important notes to keep in mind regarding the “col” tag in HTML:

  • The “col” tag is used to define a column within an HTML table, and it is always placed inside the “colgroup” tag.
  • The “col” tag does not contain any content, but it can have specific attributes that define the visual appearance of the column, such as width, alignment, and background color.
  • The “col” tag is not a required element in HTML tables. If you don’t specify any “col” tags, the browser will create default columns for you.
  • The “col” tag does not have any specific event attributes. However, you can attach events to the table cells (<td>) within a specific column.
  • It is recommended to use CSS styles instead of HTML attributes to define the visual appearance of elements, including columns in HTML tables.
  • The “col” tag is supported in all modern browsers, but some older browsers may not support all of its attributes. Make sure to test your code in different browsers to ensure cross-browser compatibility.
  • While the “col” tag is not commonly used in modern HTML development, it can be useful in certain situations, such as when you need to apply a background color or other style to a specific column in a table.

Browser Compatibility

The HTML col tag has essential support with the following browsers:

  1. Chrome
  2. Internet Explorer (IE)
  3. Opera
  4. Safari (WebKit)
  5. Firefox (Gecko)
  6. Android
  7. Firefox Mobile (Gecko)
  8. Edge Mobile
  9. Opera Mobile
  10. Safari Mobile

Examples of HTML col tag

We will discuss theHTML col tag below, with some examples of how to use the col tag in HTML5, HTML 4.01 Transitional, XHTML 1.0 Strict, XHTML 1.0 Transitional, and XHTML 1.1.

  1. HTML5
  2. HTML4
  3. XHTML

HTML5 Document

Here’s an example of how to use the “col” tag in an HTML5 document:

<!DOCTYPE html>
<html>
<head>
<title>Example Using Col Tag</title>
<style>
table, th, td {
border: 1px solid black;
border-collapse: collapse;
padding: 5px;
}
col.red {
background-color: red;
}
</style>
</head>
<body>
<h1>Example Using Col Tag</h1>
<table>
<colgroup>
<col>
<col>
<col class="red">
</colgroup>
<thead>
<tr>
<th>First Name</th>
<th>Last Name</th>
<th>Age</th>
</tr>
</thead>
<tbody>
<tr>
<td>John</td>
<td>Doe</td>
<td>30</td>
</tr>
<tr>
<td>Jane</td>
<td>Smith</td>
<td>25</td>
</tr>
<tr>
<td>Bob</td>
<td>Johnson</td>
<td>40</td>
</tr>
</tbody>
</table>
</body>
</html>

In this example, we have a simple HTML table that displays information about people. The table contains three columns: First Name, Last Name, and Age.

The “col” tag is used inside the “colgroup” tag to define the three columns. The first two columns are standard, while the third column has a class of “red” applied to it. This class is defined in the style section, and it sets the background color of the column to red.

Note that we’re using CSS styles to define the appearance of the table and the columns. This is recommended instead of using HTML attributes, as it separates presentation from content.

When you open this HTML file in a browser, you should see a table with three columns, and the third column should have a red background color.

 

HTML 4.01 Transitional Document

here’s an example of how to use the “col” tag in an HTML 4.01 Transitional document:

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<title>Example Using Col Tag</title>
<style>
table, th, td {
border: 1px solid black;
border-collapse: collapse;
padding: 5px;
}
col.red {
background-color: red;
}
</style>
</head>
<body>
<h1>Example Using Col Tag</h1>
<table>
<colgroup>
<col>
<col>
<col class="red">
</colgroup>
<thead>
<tr>
<th>First Name</th>
<th>Last Name</th>
<th>Age</th>
</tr>
</thead>
<tbody>
<tr>
<td>John</td>
<td>Doe</td>
<td>30</td>
</tr>
<tr>
<td>Jane</td>
<td>Smith</td>
<td>25</td>
</tr>
<tr>
<td>Bob</td>
<td>Johnson</td>
<td>40</td>
</tr>
</tbody>
</table>
</body>
</html>

In this example, we have a simple HTML table that displays information about people. The table contains three columns: First Name, Last Name, and Age.

The “col” tag is used inside the “colgroup” tag to define the three columns. The first two columns are standard, while the third column has a class of “red” applied to it. This class is defined in the style section, and it sets the background color of the column to red.

Note that we’re using CSS styles to define the appearance of the table and the columns. This is recommended instead of using HTML attributes, as it separates presentation from content.

When you open this HTML file in a browser, you should see a table with three columns, and the third column should have a red background color. However, note that the HTML 4.01 Transitional doctype is outdated and not recommended for use in modern HTML development. It is recommended to use the HTML5 doctype instead.

 

 

XHTML 1.0 Transitional Document

Here’s an example of how to use the “col” tag in an XHTML 1.0 Transitional document:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html
PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>Example Using Col Tag</title>
<style type="text/css">
table, th, td {
border: 1px solid black;
border-collapse: collapse;
padding: 5px;
}
col.red {
background-color: red;
}
</style>
</head>
<body>
<h1>Example Using Col Tag</h1>
<table>
<colgroup>
<col />
<col />
<col class="red" />
</colgroup>
<thead>
<tr>
<th>First Name</th>
<th>Last Name</th>
<th>Age</th>
</tr>
</thead>
<tbody>
<tr>
<td>John</td>
<td>Doe</td>
<td>30</td>
</tr>
<tr>
<td>Jane</td>
<td>Smith</td>
<td>25</td>
</tr>
<tr>
<td>Bob</td>
<td>Johnson</td>
<td>40</td>
</tr>
</tbody>
</table>
</body>
</html>

In this example, we have a simple XHTML table that displays information about people. The table contains three columns: First Name, Last Name, and Age.

The “col” tag is used inside the “colgroup” tag to define the three columns. The first two columns are standard, while the third column has a class of “red” applied to it. This class is defined in the style section, and it sets the background color of the column to red.

Note that we’re using CSS styles to define the appearance of the table and the columns. This is recommended instead of using HTML attributes, as it separates presentation from content.

When you open this XHTML file in a browser, you should see a table with three columns, and the third column should have a red background color. However, note that XHTML 1.0 is an older version of the XHTML standard and is no longer recommended for use in modern web development. It is recommended to use HTML5 instead.

 

XHTML 1.0 Strict Document

Here’s an example of how to use the “col” tag in an XHTML 1.0 Strict document:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html
PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>Example Using Col Tag</title>
<style type="text/css">
table, th, td {
border: 1px solid black;
border-collapse: collapse;
padding: 5px;
}
col.red {
background-color: red;
}
</style>
</head>
<body>
<h1>Example Using Col Tag</h1>
<table>
<colgroup>
<col />
<col />
<col class="red" />
</colgroup>
<thead>
<tr>
<th>First Name</th>
<th>Last Name</th>
<th>Age</th>
</tr>
</thead>
<tbody>
<tr>
<td>John</td>
<td>Doe</td>
<td>30</td>
</tr>
<tr>
<td>Jane</td>
<td>Smith</td>
<td>25</td>
</tr>
<tr>
<td>Bob</td>
<td>Johnson</td>
<td>40</td>
</tr>
</tbody>
</table>
</body>
</html>

In this example, we have a simple XHTML table that displays information about people. The table contains three columns: First Name, Last Name, and Age.

The “col” tag is used inside the “colgroup” tag to define the three columns. The first two columns are standard, while the third column has a class of “red” applied to it. This class is defined in the style section, and it sets the background color of the column to red.

Note that we’re using CSS styles to define the appearance of the table and the columns. This is recommended instead of using HTML attributes, as it separates presentation from content.

When you open this XHTML file in a browser, you should see a table with three columns, and the third column should have a red background color. However, note that XHTML 1.0 is an older version of the XHTML standard and is no longer recommended for use in modern web development. It is recommended to use HTML5 instead.

XHTML 1.1 Document

Here’s an example of how to use the “col” tag in an XHTML 1.1 document:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html
PUBLIC "-//W3C//DTD XHTML 1.1//EN"
"http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>Example Using Col Tag</title>
<style type="text/css">
table, th, td {
border: 1px solid black;
border-collapse: collapse;
padding: 5px;
}
col.red {
background-color: red;
}
</style>
</head>
<body>
<h1>Example Using Col Tag</h1>
<table>
<colgroup>
<col />
<col />
<col class="red" />
</colgroup>
<thead>
<tr>
<th>First Name</th>
<th>Last Name</th>
<th>Age</th>
</tr>
</thead>
<tbody>
<tr>
<td>John</td>
<td>Doe</td>
<td>30</td>
</tr>
<tr>
<td>Jane</td>
<td>Smith</td>
<td>25</td>
</tr>
<tr>
<td>Bob</td>
<td>Johnson</td>
<td>40</td>
</tr>
</tbody>
</table>
</body>
</html>

This example is very similar to the previous one, but it uses an XHTML 1.1 doctype. Note that in XHTML 1.1, all tags must be closed, even if they don’t have any content. In this case, we’re closing the “col” tags, even though they don’t have any content.

Also note that XHTML 1.1 is not as widely used as other versions of HTML and XHTML, and it has some specific requirements that may not be necessary for your project. You should carefully consider your options and requirements before deciding to use XHTML 1.1.