Getting DOM elements by classname

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I'm using PHP DOM and I'm trying to get an element within a DOM node that have a given class name. What's the best way to get that sub-element?

Update: I ended up using Mechanize for PHP which was much easier to work with.

Answers

Update: Xpath version of *[@class~='my-class'] css selector

So after my comment below in response to hakre's comment, I got curious and looked into the code behind Zend_Dom_Query. It looks like the above selector is compiled to the following xpath (untested):

[contains(concat(' ', normalize-space(@class), ' '), ' my-class ')]

So the PHP would be:

$dom = new DomDocument();
$dom->load($filePath);
$finder = new DomXPath($dom);
$classname="my-class";
$nodes = $finder->query("//*[contains(concat(' ', normalize-space(@class), ' '), ' $classname ')]");

Basically, all we do here is normalize the class attribute so that even a single class is bounded by spaces, and the complete class list is bounded in spaces. Then append the class we are searching for with a space. This way we are effectively looking for and find only instances of my-class .

Use an xpath selector?

$dom = new DomDocument();
$dom->load($filePath);
$finder = new DomXPath($dom);
$classname="my-class";
$nodes = $finder->query("//*[contains(@class, '$classname')]");

If it is only ever one type of element you can replace the * with the particular tagname.

If you need to do a lot of this with very complex selector I would recommend Zend_Dom_Query which supports CSS selector syntax (a la jQuery):

$finder = new Zend_Dom_Query($html);
$classname = 'my-class';
$nodes = $finder->query("*[class~="$classname"]");

Friday, November 4, 2022

umdigital110-1bc0468862a1

Using simpleXML:

$xml = new SimpleXMLElement($xmlstr);
echo $xml->file['path']."n";

Output:

http://www.thesite.com/download/eysjkss.zip

Friday, August 26, 2022

nicola_pesavento-a9e94f558eb3

You can use XPath on your DOMDocument as follows:

$doc->loadHTML($article_header);
$xpath = new DOMXpath($doc);

$imagesAndIframes = $xpath->query('//img | //iframe');

$length = $imagesAndIframes->length;
for ($i = 0; $i < $length; $i++) {
    $element = $imagesAndIframes->item($i);

    if ($element->tagName == 'img') {
        echo 'img';
    } else {
        echo 'iframe';
    }
}

Monday, October 17, 2022

sinned

The problem is that the NodeList returned to you is "live" - it changes as you alter the class name. That is, when you change the class on the first element, the list is immediately one element shorter than it was.

Try this:

  while (elementArray.length) {
    elementArray[0].className = "exampleClassComplete";
  }

(There's no need to use setAttribute() to set the "class" value - just update the "className" property. Using setAttribute() in old versions of IE wouldn't work anyway.)

Alternatively, convert your NodeList to a plain array, and then use your indexed iteration:

  elementArray = [].slice.call(elementArray, 0);
  for (var i = 0; i < elementArray.length; ++i)
    elementArray[i].className = "whatever";

As pointed out in a comment, this has the advantage of not relying on the semantics of NodeList objects. (Note also, thanks again to a comment, that if you need this to work in older versions of Internet Explorer, you'd have to write an explicit loop to copy element references from the NodeList to an array.)

Sunday, August 28, 2022

androidmech

This works

div {
    display:table;
}
input {
    display:table-footer-group;
}
label {
    display:table-header-group;
}

http://jsfiddle.net/v8xTC/

Friday, December 2, 2022

8bitalex

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Getting DOM elements by classname

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