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technology/files/XPath.md

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+---
+obj: concept
+wiki: https://en.wikipedia.org/wiki/XPath
+---
+
+# XPath
+XPath ([XML](XML.md) Path Language) is a powerful query language used to navigate and select elements from [XML](XML.md) documents. It is commonly employed in web scraping, [XML](XML.md) processing, and testing scenarios.
+
+## XPath Syntax
+XPath expressions use a path notation to identify and navigate [XML](XML.md) elements. The basic syntax includes:
+- **Node Selection:** `/` is used to select the root node. `element` selects all child elements of the current node with the specified name: `/root/element`   
+- **Wildcards:** The `*` symbol is used as a wildcard for any element. `/root/*`
+- **Predicates:** Square brackets `[]` are used to specify conditions for node selection. `/root/element[@attribute='value']`
+
+### Absolute XPath
+Absolute XPath provides the complete path from the root node to the desired element. It starts with a single forward slash `/`.
+`/html/body/div[1]/p[2]`
+
+### Relative XPath
+Relative XPath selects elements based on their relationship to other elements. It does not start from the root, allowing for more flexible and adaptable expressions.
+`//div[@class='example']/a`
+
+### XPath Functions
+XPath provides various functions for more complex queries. Examples include `text()`, `contains()`, and `position()`.
+`//h2[contains(text(),'XPath')]`
+
+Some functions include:
+- `text()`: The `text()` function is used to select the text content of an element.
+- `contains(element, value)`: The `contains()` function is used to check if a string contains a specific substring.
+- `starts-with(element, value)`: The `starts-with()` function is used to check if a string starts with a specified prefix.
+- `concat(elements...)`: The `concat()` function concatenates two or more strings.
+- `not(element)`: The `not()` function negates a given expression.
+- `position()`: The `position()` function returns the position of the current node in the selection.
+- `last()`: The `last()` function returns the position of the last node in the selection.