What alternative solutions are available for validating HTML tags in PHP besides regular expressions?

One alternative solution for validating HTML tags in PHP besides regular expressions is to use the DOMDocument class. This class allows you to load an HTML document and then manipulate its elements, making it easy to validate and sanitize HTML tags. 

// HTML input to validate
$html = '<p>Hello, <script>alert("XSS");</script>World!</p>';

// Create a new DOMDocument
$dom = new DOMDocument();

// Load the HTML content
$dom->loadHTML($html);

// Get all the HTML elements
$elements = $dom->getElementsByTagName('*');

// Loop through each element and remove any unwanted tags
foreach ($elements as $element) {
    $tag = $element->tagName;
    if (!in_array($tag, ['p', 'a', 'strong', 'em'])) {
        $element->parentNode->removeChild($element);
    }
}

// Get the sanitized HTML content
$sanitizedHtml = $dom->saveHTML();

echo $sanitizedHtml;

Keywords

HTML Purifier DOMDocument Tidy HTMLPurifier HTML filtering

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