DevGuru XSLT element-available function

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XSLT FUNCTION: element-available

Boolean = element-available('qname')

The element-available function is used to determine if the XSLT processor will support the use of the XSLT element cited in the argument. Currently, this is important when dealing with proprietary elements. In the future, this function will gain additional importance when you have to contend with more than one version of the W3C XSLT standard.

If the element is supported, true is returned. If the element is not supported, false is returned.

The xsl:fallback function is designed to provide fallback code that can be run as an alternative when an XSLT processor fails to support an element.

This test only applies to instruction elements, which are elements that can occur in a template body. The current W3C version of XSLT has 18 instruction elements. They are:

xsl:apply-imports	xsl:fallback
xsl:apply-templates	xsl:for-each
xsl:attributes	xsl:if
xsl:call-template	xsl:message
xsl:choose	xsl:number
xsl:comment	xsl:processing instruction
xsl:copy	xsl:text
xsl:copy-of	xsl:value-of
xsl:element	xsl:variable

'qname'

The mandatory qname argument is the qname of the element to be tested. It is commonly enclosed by single quotes.

We use the DevGuru Staff List XML file for our example with the following header:
<?xml-stylesheet type="text/xsl" href="xslt_example_element avaiable.xsl"?>
and we name it: xslt_example_element available.xml

We test to see if the xsl:aardvark element is available.

Code for xslt_example_elementavailable.xsl:

<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
<xsl:template match="/">
<html>
<body>
<xsl:choose>
<xsl:when test="element-available('xsl:aardvark')">
<xsl:text>The xsl:aardvark element is available</xsl:text>
</xsl:when>
<xsl:otherwise>
<xsl:text>The xsl:aardvark element is not available</xsl:text>
</xsl:otherwise>
</xsl:choose>
</body>
</html>
</xsl:template>
</xsl:stylesheet>

Output:

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