php preg_replace href attribute using conditions - php

Question

hello I have the following tags :
$content ='<a href="http://website.com/" />
<a href="/link1" />
<a href="https://website.com" />
<a href="link1" />';
and this code :
preg_replace('~href=(\'|"|)(.*?)(\'|"|)(?<!\/|http:\/\/|https:\/\/)~i', 'href=$1http://website2.com/$2$3', $content);
I want to use the code above to replace href tags doesn't start with an http or https or with a slash . thanks in advance.

Answer 1

Something like this should do it. I'd advise using a parser in the future, How do you parse and process HTML/XML in PHP?, for tasks such as this though. This can become very messy quickly. Here's a link on this regex usage as well, http://www.rexegg.com/regex-best-trick.html.
Regex:
/href=("|')https?:\/\/(*SKIP)(*FAIL)|href=("|')(.*?)\2/
Demo: https://regex101.com/r/cV2xB5/1
PHP Usage:
$content ='<a href="http://website.com/" />
<a href="/link1" />
<a href="https://website.com" />
<a href="link1" />';
echo preg_replace('/href=("|\')https?:\/\/(*SKIP)(*FAIL)|href=("|\')\/?(.*?)\2/', 'href=$2http://website2.com/$3$2', $content);
Output:
<a href="http://website.com/" />
<a href="http://website2.com/link1" />
<a href="https://website.com" />
<a href="http://website2.com/link1" />
Update, for // exclusion
Use:
href=("|')(?:https?:)?\/\/(*SKIP)(*FAIL)|href=("|')(.*?)\2
Demo: https://regex101.com/r/cV2xB5/2
PHP:
$content ='<a href="//website.com/" />
<a href="/link1" />
<a href="https://website.com" />
<a href="link1" />';
echo preg_replace('/href=("|\')(?:https?:)?\/\/(*SKIP)(*FAIL)|href=("|\')\/?(.*?)\2/', 'href=$2http://website2.com/$3$2', $content);
Output:
<a href="//website.com/" />
<a href="http://website2.com/link1" />
<a href="https://website.com" />
<a href="http://website2.com/link1" />