Select HTML elements with more than one css class using XPath

David Bruant at Tue, 03 Aug 2010 12:31:48 +0200

David Bruant — Tue, 03 Aug 2010 10:31:48 +0000

Interesting post and comments. Xpath 1.0 (still the only version supported in PHP) supports the start-with function (http://www.w3.org/TR/xpath/#function-starts-with) which can make your solution slightly more easily readable : //*[ contains( normalize-space( @class ), ' $classname ' ) or starts-with( normalize-space( @class ), '$classname ') or substring( normalize-space( @class ), string-length( @class ) - string-length( '$classname' ) ) = ' $classname' or @class = '$classname' ] Sadly, the ends-with function has only been added in XPath 2.0 (http://www.w3.org/TR/xquery-operators/#func-ends-with) Sam's solutions is very elegant, indeed.

edwin at Thu, 18 Feb 2010 07:43:04 +0100

edwin — Thu, 18 Feb 2010 06:43:04 +0000

Nice post.

Jakob at Sun, 13 Dec 2009 16:05:54 +0100

Jakob — Sun, 13 Dec 2009 15:05:54 +0000

@luka8088: I am glad I could help. "normalize-space" ensures every space/tab combination inbetween to classes is reduced to one simple space. This way it is ensured that the matching does work even if there are multiple spaces or tabs between the different classes. greetings, Jakob

luka8088 at Sun, 13 Dec 2009 11:01:28 +0100

luka8088 — Sun, 13 Dec 2009 10:01:28 +0000

Hi, thanks for posting this, it was very helpful ! I was hoping to find something like |= in css3, but this is also a elegant solution :) I just don't understand what is the purpose of normalize-space ? It will work the same without it ... Or it is faster that way ? Also, checking that element has a class attribute ? Is it for optimization or ? Anyway, good job and thanks :)

Nitin at Fri, 02 Oct 2009 23:31:47 +0200

Nitin — Fri, 02 Oct 2009 21:31:47 +0000

Just wanted to drop my regards to you, it helped me in one of my recent project. Thanks Jacob and Sam.

Jakob at Tue, 09 Jun 2009 17:25:43 +0200

Jakob — Tue, 09 Jun 2009 15:25:43 +0000

@Jan!: Yeah you are right. I have been in a hurry and overlooked the spaces around $classname. I thought he was proposing to search for '$classname' (without the spaces). @Sam: I am sorry about misreading your expression first. What you proposed should work without a problem. And is a really elegant solution :) Thanks for your input greetings Jakob

Jan! at Tue, 09 Jun 2009 15:50:56 +0200

Jan! — Tue, 09 Jun 2009 13:50:56 +0000

@Jakob: how exactly would Sam's method fail on that example? It would be searching for " bar " in " foobar ".

Jakob at Tue, 09 Jun 2009 13:42:54 +0200

Jakob — Tue, 09 Jun 2009 11:42:54 +0000

@Sam: The problem with this approach is that parts of classes would be matched, too. For example if

is given it would match the class "bar" or "foo", which is not the intended behaviour. @Ruben: You are right about libxslt supporting exslt, which enables us to use these functions in XSLTs. Unfortunately I needed an expression to simple Match DOM nodes inside of PHP. I didn't want to write an XSLT for it, apply it to the source document and read the result in. This seems to be a lot of unneeded hassle ;). Anyway thanks for the information about the node sets in conjunction with equal checks. This makes the XPath 2.0 expression even more elegant. greetings Jakob

Ruben Wagner at Tue, 09 Jun 2009 11:19:58 +0200

Ruben Wagner — Tue, 09 Jun 2009 09:19:58 +0000

PHP (libxslt) supports exslt (http://www.exslt.org) so you can use //div['foo' = str:tokenize(@class)] if you define the namespace "str" in your stylesheet: xmlns:str="http://exslt.org/strings" P.S. When you compare a string with a node set it returns true, if any node's value equals the string.

Sam Shull at Tue, 09 Jun 2009 04:14:35 +0200

Sam Shull — Tue, 09 Jun 2009 02:14:35 +0000

How about: //*[ @class and contains( concat( ' ', normalize-space(@class), ' ' ), ' $classname ' ) ]