$re = '/content="/m';
$str = '<!DOCTYPE HTML><html lang="en"><head><meta charset="utf-8"><title>AlifPay</title><base href="/web/"><meta name="viewport" content="width=device-width,initial-scale=1"><meta name="stk" content="1lPxBhJKqRKUG6q73mQt4wQoD5I"><link rel="icon" type="image/x-icon" href="./favicon.png"><link href="styles.99f15c62ba66cd524e55.bundle.css" rel="stylesheet"/></head><body><app-root></app-root><script type="text/javascript" src="inline.aced06935de18d27acc6.bundle.js"></script><script type="text/javascript" src="polyfills.34df2d66b4f714bfa1ad.bundle.js"></script><script type="text/javascript" src="main.0cea576e7bb8eeaea0e1.bundle.js"></script></body></html>
';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php