How to Efficiently Retrieve DOM Elements by Class Name Using PHP?

How to Retrieve DOM Elements by Class Name

Retrieving sub-elements with specific class names from DOM nodes can be achieved using various methods. Here are some approaches:

Using PHP DOM

PHP DOM provides a powerful way to manipulate HTML documents. To grab elements with a given class name, you can use Xpath selectors:

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

Using Zend_Dom_Query

This library offers a convenient interface for working with CSS selectors, making it easier to select elements:

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

Using Xpath Version of *[@class~='my-class'] CSS Selector

After further investigation, an Xpath version of the CSS selector was discovered:

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

Utilizing this xpath in PHP:

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

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