this is if you have an element as follows, and you want to extract attributes from it.

<img class="an-image-wow" src="image.jpg" data-image="data-image.jpg" alt="my alt tag">

list all its attributes too see which ones we can access

foreach($html->find('img[data-original]') as $img) {
  	var_dump($img->attr);
}

here is how you extract the data-image information

foreach($html->find('img[data-original]') as $img) {
	echo $img->attr['data-original']; // works!!!
	echo "<br>";
}