Edit and manipulate class and data-attributes of DOM elements with PHP - php

Question

I have some HTML snippets retrieved through PHP/JSON such as:
<div>
<p>Some Text</p>
<img src="example.jpg" />
<img src="example2.jpg" />
<img src="example3.jpg" />
</div>
I am loading it with DOMDocument() and xpath and would like to be able to manipulate it so I can add lazy loading to the images like so:
<div>
<p>Some Text</p>
<img class="lazy" src="blank.gif" data-src="example.jpg" />
<img class="lazy" src="blank.gif" data-src="example2.jpg" />
<img class="lazy" src="blank.gif" data-src="example3.jpg" />
</div>
Which entails:
Add class .lazy
Add data-src attribute from original src attribute
Modify src attribute to blank.gif
I am trying the following but it isn't working:
foreach ($xpath->query("//img") as $node) {
$node->setAttribute( "class", $node->getAttribute("class")." lazy");
$node->setAttribute( "data-src", $node->getAttribute("src"));
$node->setAttribute( "src", "./inc/image/blank.gif");
}
but it isn't working.

Answer 1

Are you sure? The following works for me.
<?php
$html = <<<EOQ
<div>
<p>Some Text</p>
<img src="example.jpg" />
<img src="example2.jpg" />
<img src="example3.jpg" />
</div>
EOQ;
$dom = new DOMDocument();
$dom->loadHTML($html);
$xpath = new DOMXPath($dom);
foreach ($xpath->query('//img') as $node) {
$node->setAttribute('class', $node->getAttribute('class') . ' lazy');
$node->setAttribute( "data-src", $node->getAttribute("src"));
$node->setAttribute( "src", "./inc/image/blank.gif");
}
echo $dom->saveHTML();