preg_replace img src to data-src stack overflow (PHP)
Question
I using lazyload script for iframes I need to make a preg_replace code to change src to data-src.
I try something like this but I failed:
$cache = preg_replace('%<iframe.*?src=["\'](.*?)["\'].*?/?>%i', 'data-src="$1"', $content);
My code is only print data-src="the link" without the full iframe code.
1 answers
solution1
4 ACCPTED 2017-11-29 05:56:43
New Answer that uses legitimate DOM parsering functions to reliably mutate valid html:
- Iterate all iframe tags.
- Insert the new
data-srcattribute using the existingsrcattribute. - Remove the old
srcattribute. - Print the updated DOM.
As mentioned by @user706420, removing the src attribute from the <iframe> tag is a bad decision because it renders the html invalid. My answer is demonstrative on how to execute a tag attribute replacement generally, but I agree with @user706420 that this task does seem logically flawed.
Code: ( Demo )
$html = <<<HTML
<p>Some random text <iframe src="the link"" width="425" height="350" frameborder="0"></iframe></p>
HTML;
libxml_use_internal_errors(true);
$dom = new DOMDocument;
$dom->loadHTML($html, LIBXML_HTML_NOIMPLIED | LIBXML_HTML_NODEFDTD);
foreach ($dom->getElementsByTagName('iframe') as $iframe) {
$iframe->setAttribute('data-src', $iframe->getAttribute('src'));
$iframe->removeAttribute('src');
}
echo $dom->saveHTML();
Output:
<p>Some random text <iframe width="425" height="350" frameborder="0" data-src="the link"></iframe></p>
Old Answer (improved on Oct 9, 2020) with advice that I no longer endorse because regex is "DOM-ignorant"...
Match the start of the <iframe and all characters within the opening tag until you encounter a space character which is followed immediately by the substring src= -- this ensures that the targeted src= substring doesn't have any preceding non-white-space characters (IOW, it is a whole/solitary word).
The substring before the space must be released/forgotten -- this is what \\K does. The space will need to be consumed and replaced with data- .
Code: ( Demo )
$content = 'Some text that contains src <iframe src="www.example.com"/> Some text';
echo preg_replace('~<iframe[^>]*\K (?=src=)~i', ' data-', $content);
Output:
Some text that contains src <iframe data-src="www.example.com"/> Some text
Although I have improved the regex, valid html strings can see be intentionally written to break the regex like: <iframe src="www.example.com"/ data-type="<iframe" data-whoops=" src= oh my"> For this reason, I ONLY recommend parsing html with a dom parser.
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