Question

So this doesn’t work:

        foreach ($element->attributes as $attribute) {
            $element->removeAttribute($attribute->name);
        }

If the node has 2 attributes, it only removes the first one.

I tried cloning the DOMNamedNodeMap with no success:

        $attributesCopy = clone $element->attributes;
        foreach ($attributesCopy  as $attribute) {
            $element->removeAttribute($attribute->name);
        }

Still removes only first attribute.

This issue is explained here: http://php.net/manual/en/class.domnamednodemap.php
Apparently it is a feature, not a bug. But there is no solution mentioned in the comments.

Answer 1

Simply:

$attributes = $element->attributes;
while ($attributes->length) {
    $element->removeAttribute($attributes->item(0)->name);
}

Since the attributes collection automatically reindexes as soon as an attribute is removed, just keep on removing attribute zero until none are left.