XPath axes (Axes)
Shaft means relative to the set of nodes of the current node
| Axis name | result |
|---|---|
| ancestor | Select all ancestors of the current node (parent, grandparent, etc.) |
| ancestor-or-self | Select all the ancestors of the current node (parent, grandparent, etc.) as well as the current node itself |
| attribute | Select all the attributes of the current node. @id equivalent to attribute :: id |
| child | Select all child elements of the current node, title equivalent to child: title |
| descendant | Select all the elements of the current node descendant (son, Sun, etc.) |
| descendant-or-self | Select all descendants of the current node's operation (sub, Sun, etc.) and the current node itself |
| following | All nodes after the end of the tab, select the document in the current node |
| namespace | Select all the namespace of the current node |
| parent | Select the parent of the current node |
| preceding | Select the parent of the current node |
| preceding-sibling | Prior to the selection of the current node all of the peer nodes |
| self | Select the current node. And other control self :: node () |
Example:
| example | meaning |
|---|---|
| parent::div | Upper parent node, you called biological father div, there is at most one; |
| child::div | Underlying all child nodes, all your own child named in the div; |
| ancestor::div | Above all immediate node, you are my father biological father or your own father or your own father called in the div; |
| descendant::div | All of the following nodes, your offspring called div, not including the offspring for your brother; |
| following::div | Since all nodes in the following pages you call the div; |
| following-sibling::div | Under the same layer node, all your younger brother in a div called; |
| preceding::div | On the same layer node, all of your elder brother and their descendants called the div; |
| preceding-sibling::div | On the same layer node, all of your elder brother in a div called; |
Step Step
Syntax axis names steps: node test [predicate]
| example | result |
|---|---|
| child::book | Select the book belongs to all nodes of the current node only elements |
| attribute :: long | Select lang attribute of the current node |
child::* |
Select all the elements of the current node only |
attribute::* |
Select all attributes of the current node |
| child::text() | Select all the text of the current node child nodes |
| child::node() | Select all child nodes of the current node |
| descendant::book | Select all book descendants of the current node |
| ancestor:book | Select all book ancestors of the current node |
| ancestor-or-self::book | Select all book ancestors of the current node and the current node (if the node is a book node) |
child::*/child::price |
Select all of the current node price Sun |
Examples
//a/parent::h3
//div[@price<100]/child::div
//div[@price<100]/descendant::h2
//a/ancestor::div
//div[@id="testid"][2]/following::div
//div[@id="testid"][2]/following::li
//div[@id="testid"][2]/following-sibling::div[@id="go"]
//div[@id="testid"]/preceding::ul
//div[@id="testid"][2]/preceding-sibling::div
//a/attribute::href
//h3/child::*
Select all the elements of the current node only
All exercises code: https://github.com/SaltNego/Web_Crawler_Notes
