Question

I don’t understand why we should use text() instead of just using “.”
What is the difference?

//library/book/author[text() = "An Author"]

vs

//span[@class="whateverclass"][. = "An Author"]

Answer 1

The difference is probably best illustrated with an example, where an element has one or more child elements, and multiple text elements (an element is allowed multiple text elements interspersed between child elements):

<element>
  text1
  <child>
     child1text1
  <child>
  text2
</element>

Assuming element is current:

• . will return text1 child1text1 text2 (with whitespace)
• text()[1] will return text1
• text()[2] will return text2

Of special note is text() will behave differently in xslt 1.0 vs xslt 2.0

• text() returns just text1 in xslt 1.0
• text() returns text1 text2 (with whitespace) in xslt 2.0