XPath

XPath Selectors {.cols-6}

Getting started {.col-span-2}

• Xpath test bed (whitebeam.org)

Test in Firefox or Chrome console:

$x('/html/body')
$x('//h1')
$x('//h1')[0].innerText
$x('//a[text()="XPath"]')[0].click()

Descendant selectors {.col-span-2}

Xpath	CSS
//h1	h1
//div//p	div p
//ul/li	ul > li
//ul/li/a	ul > li > a
//div/*	div > *
/	:root
/html/body	:root > body

{.show-header}

Order selectors {.col-span-2}

Xpath	CSS
//ul/li[1]	ul > li:first-child
//ul/li[2]	ul > li:nth-child(2)
//ul/li[last()]	ul > li:last-child
//li[@id="id"][1]	li#id:first-child
//a[1]	a:first-child
//a[last()]	a:last-child

{.show-header}

Attribute selectors {.col-span-3 .row-span-2}

Xpath	CSS
//*[@id="id"]	#id
//*[@class="class"]	.class
//input[@type="submit"]	input[type=“submit”]
//a[@id="abc"][@for="xyz"]	a#abc[for=“xyz”]
//a[@rel]	a[rel]
//a[starts-with(@href, '/')]	a[href^=’/‘]
//a[ends-with(@href, '.pdf')]	a[href$=‘pdf’]
//a[contains(@href, '://')]	a[href*=‘://‘]
//a[contains(@rel, 'help')]	a[rel~=‘help’]

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Siblings {.col-span-3}

Xpath	CSS
//h1/following-sibling::ul	h1 ~ ul
//h1/following-sibling::ul[1]	h1 + ul
//h1/following-sibling::[@id="id"]	h1 ~ #id

{.show-header}

jQuery {.col-span-3}

Xpath	CSS
//ul/li/..	$(‘ul > li’).parent()
//li/ancestor-or-self::section	$(‘li’).closest(‘section’)
//a/@href	$(‘a’).attr(‘href’)
//span/text()	$(‘span’).text()

{.show-header}

Misc selectors {.col-span-3}

| Xpath | CSS | | --------------------------------- | ------------------------- | --------------------- | | //h1[not(@id)] | h1:not([id]) | | //button[text()="Submit"] | Text match | | //button[contains(text(),"Go")] | Text contains (substring) | | //product[@price > 2.50] | Arithmetic | | //ul[*] | Has children | | //ul[li] | Has children (specific) | | //a[@name or @href] | Or logic | | //a | //div | Union (joins results) |

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XPath Expressions

Steps and axes {.secondary}

-	-	-	-
//	ul	/	a[@id='link']
Axis	Step	Axis	Step

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Prefixes

Prefix	Example	Means
//	//hr[@class='edge']	Anywhere
/	/html/body/div	Root
./	./div/p	Relative

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Axes

Axis	Example	Means
/	//ul/li/a	Child
//	//[@id="list"]//a	Descendant

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XPath Predicates

Predicates

//div[true()]
//div[@class="head"]
//div[@class="head"][@id="top"]

Restricts a nodeset only if some condition is true. They can be chained.

Operators

# Comparison
//a[@id = "xyz"]
//a[@id != "xyz"]
//a[@price > 25]

# Logic (and/or)
//div[@id="head" and position()=2]
//div[(x and y) or not(z)]

Using nodes

# Use them inside functions
//ul[count(li) > 2]
//ul[count(li[@class='hide']) > 0]

# Returns `<ul>` that has a `<li>` child
//ul[li]

You can use nodes inside predicates.

Indexing

//a[1]                # first <a>
//a[last()]           # last <a>
//ol/li[2]            # second <li>
//ol/li[position()=2] # same as above
//ol/li[position()>1] #:not(:first-child)

Use [] with a number, or last() or position().

Chaining order

a[1][@href='/']
a[@href='/'][1]

Order is significant, these two are different.

Nesting predicates

//section[.//h1[@id='hi']]

This returns <section> if it has an <h1> descendant with id='hi'.

XPath Functions {.cols-2}

Node functions

name()            # //[starts-with(name(), 'h')]
text()            # //button[text()="Submit"]
                  # //button/text()
lang(str)
namespace-uri()

count()           # //table[count(tr)=1]
position()        # //ol/li[position()=2]

String functions

contains()        # font[contains(@class,"head")]
starts-with()     # font[starts-with(@class,"head")]
ends-with()       # font[ends-with(@class,"head")]

concat(x,y)
substring(str, start, len)
substring-before("01/02", "/")  #=> 01
substring-after("01/02", "/")   #=> 02
translate()
normalize-space()
string-length()

Boolean functions

not(expr)         # button[not(starts-with(text(),"Submit"))]

Type conversion

string()
number()
boolean()

XPath Axes {.cols-2}

Using axes

//ul/li                       # ul > li
//ul/child::li                # ul > li (same)
//ul/following-sibling::li    # ul ~ li
//ul/descendant-or-self::li   # ul li
//ul/ancestor-or-self::li     # $('ul').closest('li')

---

//	ul	/child::	li
Axis	Step	Axis	Step

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Steps of an expression are separated by /, usually used to pick child nodes. That’s not always true: you can specify a different “axis” with ::.

Child axis

ul/li/a

# both the same
//child::ul/child::li/child::a

child:: is the default axis. This makes //a/b/c work.

# both the same
# this works because `child::li` is truthy
//ul[li]
//ul[child::li]

# both the same
//ul[count(li) > 2]
//ul[count(child::li) > 2]

Descendant-or-self axis

div//h4

# both the same
//div/descendant-or-self::h4

// is short for the descendant-or-self:: axis.

# both the same
//ul//[last()]
//ul/descendant-or-self::[last()]

Other axes {.row-span-2}

Axis	Abbrev	Notes
ancestor
ancestor-or-self
attribute	@	@href is short for attribute::href
child		div is short for child::div
descendant
descendant-or-self	//	// is short for /descendant-or-self::node()/
namespace
self	.	. is short for self::node()
parent	..	.. is short for parent::node()
following
following-sibling
preceding
preceding-sibling

{.headers}

There are other axes you can use.

Unions

//a | //span

Use | to join two expressions.

XPath More examples {.cols-2}

Examples

//*                 # all elements
count(//*)          # count all elements
(//h1)[1]/text()    # text of the first h1 heading
//li[span]          # find a <li> with an <span> inside it
                    # ...expands to //li[child::span]
//ul/li/..          # use .. to select a parent

Find a parent

//section[h1[@id='section-name']]

Finds a <section> that directly contains h1#section-name

//section[//h1[@id='section-name']]

Finds a <section> that contains h1#section-name. (Same as above, but uses descendant-or-self instead of child)

Closest

./ancestor-or-self::[@class="box"]

Works like jQuery’s $().closest('.box').

Attributes

//item[@price > 2*@discount]

Finds <item> and check its attributes

Also see

• Devhints (devhints.io)
• Xpath test bed (whitebeam.org)