XPath Predicate

XPath Predicate

XPath Predicate refers to the XPath expression written in square brackets. It refers to restrict the selected nodes in a node set for some condition.

XPath Predicates are used to find a specific node or a node that contains a specific value.

note

XPath Predicates are always embedded in square brackets.

Example

Consider the following XML document:

<?xml version="1.0"  encoding="UTF-8"?>

<bookstore>
	<book>
		<title lang="en">A Great Book</title>
		<author>Tom Nolan</author>
		<price>19.99</price>
	</book>

	<book>
		<title lang="en">Learning XML</title>
		<author>Tutorial Reference</author>
		<price>29.99</price>
	</book>
</bookstore>

In the following table there are some path expressions with predicates and the result of the expressions:

Path Expression	Result
/bookstore/book[1]	Selects the first book element that is the child of the bookstore element.
/bookstore/book[last()]	Selects the last book element that is the child of the bookstore element
/bookstore/book[last()-1]	Selects the last but one book element that is the child of the bookstore element
/bookstore/book[position()<3]	Selects the first two book elements that are children of the bookstore element
//title[@lang]	Selects all the title elements that have an attribute named lang
//title[@lang='en']	Selects all the title elements that have a "lang" attribute with a value of "en"
/bookstore/book[price>15.00]	Selects all the book elements of the bookstore element that have a price element with a value greater than 15.00
/bookstore/book[price>15.00]/title	Selects all the title elements of the book elements of the bookstore element that have a price element with a value greater than 15.00

note

In IE 5,6,7,8,9 first node is[0], but according to W3C, it is [1].

To solve this problem in IE, set the SelectionLanguage to XPath.

In JavaScript, you can do in this way: xml.setProperty("SelectionLanguage","XPath");