w3resource

HTML longdesc attribute

longdesc

The purpose of the HTML longdesc attribute is to specify a link to a long textual description for images, iframes and frames.

When used with img element, it complements alt attribute of img. When used with iframe and frame elements, it complements title attribute.

Supported elements

HTML longdesc attribute supports img, iframe and frame elements.

Syntax

<ElementName longdesc="value" >.....</ElementName>

Where ElementName is any supported elements.

Type of value

URI.

Value

A URI.

Default value

There is no default value of HTML longdesc attribute.

Supported doctypes

When used with img element, HTML 4.01 strict, HTML 4.01 transitional, HTML 4.01 frameset. When used with iframe and frame elements, HTML 4.01 frameset.

Example of HTML longdesc attribute with img

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<title>Example of HTML longdesc attribute with img </title>
</head>
<body>
<img src="../../images/w3logo5.gif" alt="The w3resource logo "     longdesc="logo.txt"/>
</body>
</html>

Result

html longdesc attribute with img

View this example in a separate browser window

Example of HTML longdesc attribute with img

Note

In the real world, usage of longdesc is rare with respect to img element. But writing a long description for iframe and frame is near appropriate.

Example of HTML longdesc attribute with frame

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<title>Example of HTML longdesc attribute with frame</title>
</head>
<frameset rows="20%,*,20%" >  
<frame src="header.html" frameborder="1"  name="header" title="Header window"/>  
<frame src="content.html" frameborder="0"  name="content" title="Content window" longdesc="content-description.txt"/>
<frame src="footer.html" frameborder="0"  name="footer" title="footer window" longdesc="footer-description.txt"/> 
</frameset>
</body>
</html>

Result

html longdesc attribute with frame

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Example of HTML longdesc attribute with frame

Example of HTML longdesc attribute with iframe

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<title>Example of HTML longdesc attribute with iframe</title>
</head>
<body>
<iframe src="../../sql/customer.php" height="100%" width="540" frameborder="1" title="The customer inforamtion " longdesc="customer.txt"> </iframe> 
</body>
</body>
</html>

Result

html longdesc attribute with iframe

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Example of HTML longdesc attribute with iframe

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