$x("string-length(//h3[@class='t'])")
8
$x("string(//h3[@class='t'])")
"XPath 教程"
$x("round(//h3[@class='t'])")
NaN
$x("number(//h3[@class='t'])")
NaN
$x("not(//h3[@class='t'])")
false
$x("normalize-space(//h3[@class='t'])")
"XPath 教程"
$x("namespace-uri(//h3[@class='t'])")
"http://www.w3.org/1999/xhtml"
$x("name(//h3[@class='t'])")
"h3"
$x("name(//local-name[@class='t'])")
""
$x("local-name(//h3[@class='t'])")
"h3"
$x("lang(//h3[@class='t'])")
false
$x("id(//h3[@class='t'])")
[]
$x("floor(//h3[@class='t'])")
NaN
$x("count(//h3[@class='t'])")
9
$x("ceiling(//h3[@class='t'])")
NaN
$x("boolean(//h3[@class='t'])")
true
