boolean Function

  • Article

Converts the argument to a Boolean.

boolean boolean(arg)

Remarks

This function converts arguments to Booleans according to the following rules.

  • If the argument is a negative or positive number, it is converted to the Boolean value true. If the argument is zero or an NaN value, it is converted to false.

  • If the argument is a non-empty node-set, it is converted to true. An empty node-set is converted to false.

  • If the argument is a non-empty string, it is converted to true. An empty string is converted to false.

  • If the argument is an object of a type other than the four basic types, it is converted to a Boolean in a way that is dependent on that type.

Example

XML File

None; the XSLT file calls itself.

If you use the sample XML file, books.xml, and change the href attribute to reference bool.xsl, boolean(//book) resolves as true.

XSLT File (bool.xsl)

<?xml version='1.0'?>
<?xml-stylesheet type="text/xsl" href="bool.xsl"?>
<xsl:stylesheet version="1.0"
      xmlns:xsl="https://www.w3.org/1999/XSL/Transform">
<xsl:output method="html"/>

<xsl:template match="/">
    <html>
       <body>
          <h3>boolean() Function</h3>
          
          <ul>
             <li><b>boolean(0)</b> = 
                <xsl:value-of select="boolean(0)"/>
             </li>
             <li><b>boolean(1)</b> = 
                <xsl:value-of select="boolean(1)"/>
             </li>
             <li><b>boolean(-100)</b> = 
                <xsl:value-of select="boolean(-100)"/>
             </li>
             <li><b>boolean(100)</b> = 
                <xsl:value-of select="boolean(100)"/>
             </li>
             <li><b>boolean(NaN)</b> = 
                <xsl:value-of select="boolean(NaN)"/>
             </li>
             <li><b>boolean('hello')</b> = 
                <xsl:value-of select="boolean('hello')"/>
             </li>
             <li><b>boolean('')</b> = 
                <xsl:value-of select="boolean('')"/>
             </li>
             <li><b>boolean(//book)</b> = 
                <xsl:value-of select="boolean(//book)"/>
             </li>
             <li><b>boolean(//notfound)</b> = 
                <xsl:value-of select="boolean(//notfound)"/>
             </li>
          </ul>
       </body>
    </html>
</xsl:template>

</xsl:stylesheet>

Formatted Output

boolean() Function

  • boolean(0) = false

  • boolean(1) = true

  • boolean(-100) = true

  • boolean(100) = true

  • boolean(NaN) = false

  • boolean('hello') = true

  • boolean('') = false

  • boolean(//book) = false

  • boolean(//notfound) = false

Processor Output

<html>

<body>

<h3>boolean() Function</h3>

<ul>

<li><b>boolean(0)</b> =

false</li>

<li><b>boolean(1)</b> =

true</li>

<li><b>boolean(-100)</b> =

true</li>

<li><b>boolean(100)</b> =

true</li>

<li><b>boolean(NaN)</b> =

false</li>

<li><b>boolean('hello')</b> =

true</li>

<li><b>boolean('')</b> =

false</li>

<li><b>boolean(//book)</b> =

true</li>

<li><b>boolean(//notfound)</b> =

false</li>

</ul>

</body>

</html>

See Also

Reference

XML Data Types Reference

Concepts

NaN Values