$re = '/[\/^](leaflet|mapbox)[\-\._]?([\w\-\._]*)\.js\??/';
$str = 'leaflet-0.7.2.js
^leaflet-0.7.2.js <-- Does anyone actually uses "^" in a filename?
/leaflet-0.7.2.js
http://leafletjs.com/dist/leaflet.js
https://api.tiles.mapbox.com/mapbox.js/v1.6.3/mapbox.js
http://example.com/path/to/leaflet-0.7.2.js
http://example.com/path/to/mapbox-v1.6.2.js
';
preg_match_all($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