"<i>Why<\/i>为什么<\/b><xsl:value-of select="1"\/><i>returns 1?<\/i>返回 1?<\/b>"

Question

I'm transforming XML to HTML using a XSLT Stylesheet. The tansformation engine is provided by Apache Xalan (Version 2.7.0). A Sax Parser is configured to be used.

If

<xsl:value-of select="1"/>

is used to transform

<element>
    <hello>Hello World</hello>
</element>

Output

1

According to https://www.w3schools.com/xml/xsl_value_of.asp the xsl:value-of-Tag extracts the value of a selected node based on the given XPath Expression.

• Why is the output 1 though there is no node 1?
• How does this simple transformation work?

Answer 1

The xsl:value-of instruction returns the result of evaluating the expression contained in its select attribute (after converting the result to a string).

An XPath expression can contain numbers, string literals, references to nodes or variables, function calls and operators. The expression 1 is evaluated as the number 1. There can be no node whose name is 1 (an element name cannot start with a digit).

Answer 2

By using the code