The XPath language is extremely powerful. You can use it to manipulate several different elements on a website. These elements include Predicates, Functions, Expressions, and much more. To learn more about XPath, read this article. It will give you the basics of this powerful language.
Table of Contents
XPath
The XPath language is used in XSLT, which uses to address code segments in an XML document. Its APIs are based on the DOM Level 3 XPath specification. The tutorial assumes no prior knowledge of XSLT and walks the reader through the background, context, structure, and concepts of XPath.
XPath’s built-in functions allow you to perform sophisticated matching on attribute values. For example, you can use the name() function to determine if a tag contains a specific attribute. This function returns true if the attribute s1 contains s2, or false if it does not.
XPath can be confusing, but it’s possible to learn its basic components by following this tutorial. XPath is used in automation testing and manual testing, and many popular automation tools use it. For example, Appium studio is a popular automation tool for testing mobile apps, and it includes a built-in XPath feature. Selenium, another popular automation tool, uses XPath to identify elements on a page.
Predicates
Predicates are expressions that restrict the nodes that an XPath expression can select. These expressions are written in square brackets and are generally true or false. A simple example of a predicate would be the expression “name:all”. This example would select the element containing the name of each employee.
Predicates are useful for limiting the set of nodes that an XPath expression can select. Each predicate is a single-word expression that returns a Boolean value (true or false). Nodes that match a predicate remain in the result node-set, while nodes that do not match it are excluded from the set. You can use a combination of predicates to define the criteria you’d like to search for.
There are two types of axes: the child axis and the parent axis. Child axes select all nodes below a given node. The child axis selects nodes that have the same parent as the context node. When a child axis is not specified, the result will be an empty node-set.
Functions
The XPath language provides several functions for finding dynamic elements within web pages. Some of these functions are ancestors, following-sibling, parent, and preceding child. The following-sibling function matches a string starting with a certain character. It can also be used to locate an element whose value is static.
XPath expressions are evaluated for each matched element and are usually composed of common and unique parts. For example, when there are two table contents on a web page, evaluating one of them will tell you the results of the remaining XPath expressions. The first node in the set will be evaluated first.
XPath expressions can reference any node in an XML document. If there is a ‘key’ element, then this element means that the XPath expression is a reference to that node. Other axes are not valid XPath expressions.
Expressions
XPath expressions allow you to select only certain nodes within an XML document. These nodes include element nodes, text nodes, and attribute nodes. Predicates are used to limit the selection and are enclosed within square brackets. The following example shows how to use a predicate to select a node:
Using an XPath expression to select a node is incredibly powerful. You can specify the location of a node and return a node set or a single node. There are many types of expressions you can create with XPath, and the basic syntax is similar to the DOM model created by the W3C. When you specify an expression, remember that the root is not necessarily the XML root element. Other nodes in an XPath expression include processing instructions, comments, and namespace declarations.
You can also use XPath functions to select a collection of nodes and return a string, number, or Boolean value. For example, if you are looking for a PROJECT node, you can use /PROJECT/text() to return the PROJECT nodes’ string values. XPath functions differ slightly from one another and depend on the context in which they are used.
Examples
XPath syntax is used to select elements in a tree. There are two types of nodes: the child node and the parent node. A child node matches an element within the same level as it. In this example, the child node matches a div element. A parent node matches an element within a different level.
An XPath expression can specify various parts of an XML document. The nodes must be declared in the XML document to match an expression. Similarly, a node set can be defined using an XPath expression.
