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It is a flexible and powerful language for querying xml or (x) html elements of a document and xslt transformations over the DOM, which is a W3C standard .
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//*[@id="w3c_home_upcoming_events"]/ul/li//a |
Basic syntax
Paths
Expression | Description |
|---|---|
. | current context |
.// | recursive descent (zero or more levels from the current context) |
/html/body | absolute path |
a | relative path |
//* | everything in the current context |
li/*/a | links that are "grandchildren" for li |
//a|//button | links and buttons (union of two sets of nodes) |
Relations
Expression | Description |
|---|---|
a/i/parent::p | immediate parent <p> |
p/ancestor::* | all parents |
p/following-sibling::* | all next brothers |
p/preceding-sibling::* | all previous brothers |
p/following::* | all of the following elements except descendants |
p/preceding::* | all previous elements except ancestors |
p/descendant-or-self::* | context node and all its descendants |
p/ancestor-or-self::* | context node and all its ancestors |
Getting nodes
Expression | Description |
|---|---|
/div/text() | get text nodes |
/div/text()[1] | get the first text node |
Item position
Expression | Description |
|---|---|
a[1] | first element |
a[last()] | last element |
a[2] | second link |
a[position() <= 3] | first 3 links |
ul[li[1]=”OK”] | list (UL) whose first element contains the value 'OK' |
tr[position() mod 2 = 1] | odd elements |
tr[position() mod 2 = 0] | even elements |
p/text()[2] | second text node |
Attributes and Filters
[] - indicates filtering items
Expression | Description |
|---|---|
input[@type=”text”] | <input> tag with type attribute equal to text |
input[@class='OK'] | <input> tag whose class attribute is OK |
p[not(@*)] | paragraphs without attributes |
*[@style] | all elements with style attribute |
a[. = “OK”] | links with the value "OK" |
a/@id | link identifiers |
a/@* | all link attributes |
| links that contain id and rel attributes |
a[i or b] | links contain an <i> or <b> element |
Functions
Basic Xpath functions - http://www.w3.org/TR/xpath/#corelib
Function | Description | Example |
|---|---|---|
name() | Returns the name of the element | [name()='a'] |
string(val) | Get attribute value | string(a[1]/@id) |
substring(val, from, to) | Cut part of a line | substring(@id, 1, 6) |
substring-before(val, to) | Return the part of the string val before the string to | substring-before('12-May-1998', '-') = '12' |
substring-after(val, from) | Return part of string val after string to | substring-after('12-May-1998', '-') = 'May-1998' |
string-length() | Returns the number of characters in a string | [string-length(text()) > 5] |
count() | Returns the number of items | |
concat() | Takes two or more strings as input and returns the concatenation (string addition) of its arguments. | |
normalize-space() | Analog Trim | [normalize-space(text())='SEARCH'] |
starts-with() | Starts with | [starts-with(text(), 'SEARCH')] |
contains() | Contains | [contains(name(), 'SEARCH')] |
translate(val, from, to) | Replaces the characters of its first string argument, which are present in the second argument, with the corresponding characters of the third argument. | translate(«bar»,«abc»,«ABC») |
Grouping
Expression | Description |
|---|---|
(table/tbody/tr)[last()] | last <tr> row from all tables |
(//h1|//h2)[contains(text(), 'Text')] | a first or second level heading that contains "Text" |
a[//tr/@data-id=@data-id] | all links whose data-id attribute matches the same attribute for a table row |
Useful links
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