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Editorial Team
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Asked: 2026-06-04T14:26:01+00:00

I am attempting to use PHP to edit the DOM document tree. However, I

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I am attempting to use PHP to edit the DOM document tree. However, I am stuck. After loading the HTML, I want to remove every element EXCEPT a select few that I specify. (<p> and <b>, for example) How can I do this? Is it even possible?

Below is my current code:

<?php
$url = 'http://en.wikipedia.org/w/index.php?title=Elephant&action=render';
$curl = curl_init();
curl_setopt($curl, CURLOPT_URL, $url);
curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($curl, CURLOPT_USERAGENT, 'Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.13) Gecko/20080311 Firefox/2.0.0.13');

$html = '<html>' . curl_exec($curl) . '</html>';
echo $html;

$document = new DOMDocument;
$document->loadHTML($html);

$allowed_elements = array(
    'a',
    'b',
    'i',
    'p',
);

$parent = $document->getElementsByTagName('html')->item(0);

foreach ($parent->getElementsByTagName('*') as $element)
{
    $node = strtolower((string)$element->nodeName);
    if (!in_array($node, $allowed_elements))
    {
        $element->parentNode->removeChild($element);
    }
}

echo $document->saveHTML();

curl_close($curl);
?>

My tinkering has shown me that it is possible to loop through the DOM tree, so I assume I could just loop through it. However, my code still isn’t working! I’m trying to get the plaintext Wikipedia article ultimately–if someone knows an alternate tool that I don’t have to write myself, that’ll be an acceptable answer.

Thanks!! 🙂

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1 Answer

  1. Editorial Team

    Try this:

    <?php
$url = 'http://en.wikipedia.org/w/index.php?title=Elephant&action=render';
$curl = curl_init();
curl_setopt($curl, CURLOPT_URL, $url);
curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($curl, CURLOPT_USERAGENT, 'Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.13) Gecko/20080311 Firefox/2.0.0.13');

$html = '<html>' . curl_exec($curl) . '</html>';
curl_close($curl);

$document = new DOMDocument('1.0');
$document->loadHTML($html);

$allowed_elements = array('a','b','i','p');
$elems = array();

$parent = $document->getElementsByTagName('html')->item(0);

foreach ($parent->getElementsByTagName('*') as $element)
{
    $node = (string)$element->nodeName;
    if(strtolower($node) == 'body'){
        continue;
    }

    $elems[] = $node;
}

$elems = array_values( array_unique( $elems ) );
$elems = array_diff( $elems, $allowed_elements );
$elems = array_values( array_unique( $elems ) );
sort($elems);

foreach( $elems as $elem ) {
    $parent1 = $parent->getElementsByTagName($elem);
    $length = $parent->getElementsByTagName($elem)->length;

    for($i=0;$i<$length;$i++) {
        $el = $parent1->item(0); // 0 is the index because after each `removeChild`, the next element shifts 1 position back.
        if( $el ) {
            $el->parentNode->removeChild($el);
        }
    }
}

echo $document->saveHTML();
?>

    $elementsToKeep – The array containg the list of items which are not to be deleted.

    Hope this helps.

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