How Can I Find DOM Elements by Class Name in PHP?

Finding Elements by Class Name in DOM

When working with a PHP DOM node, you may need to access sub-elements based on their class names. To accomplish this, there are several approaches available:

XPath Selector

XPath selectors allow you to query XML or HTML documents using XPath syntax. You can use the following XPath expression to get elements with a specific class name:

//*[contains(@class, '$classname')]

Replace $classname with the target class name. For example:

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

Zend_Dom_Query

Zend_Dom_Query provides a flexible way to query HTML or XML documents using CSS selector syntax. It supports various selectors, including the class attribute selector. To use Zend_Dom_Query:

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

CSS Selector

PHP does not natively support CSS selectors. However, you can use an external library such as Simple HTML DOM Parser to parse HTML and use CSS selectors to find elements. For example:

$html = new simple_html_dom();
$html->load($htmlDocument);
$elements = $html->find('.my-class');

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

This approach involves using Xpath to execute a somewhat complex expression that emulates the CSS selector [[@class~='my-class']*:

$xpath = "//*[contains(concat(' ', normalize-space(@class), ' '), ' my-class ')]";

Ultimately, the best approach for getting DOM elements by class name depends on your specific requirements and the available resources in your PHP environment.

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