public function firstImageUrl(string $markdown): string
    {
        $regex      = '/(?<=^|[\s;,])\!\[[^\v[\]]*\]\((?<url>https?\:\/\/[^\s()]+?\.(?:png|jpeg|jpg|gif))\)(?=$|[\s.!?;,])/ui';
        return $url = $markdown && preg_match($regex, $markdown, $_m) ? $_m['url'] : '';
    }
public function firstImageUrl(string $markdown): string
    {
        $regex      = '/(?<=^|[\s;,])\!\[[^\v[\]]*\]\((?<url>https?\:\/\/[^\s()]+?\.(?:png|jpeg|jpg|gif))\)(?=$|[\s.!?;,])/ui';
        return $url = $markdown && preg_match($regex, $markdown, $_m) ? $_m['url'] : '';
    }
public function firstImageUrl ( string $ markdown ) : string { $ regex = '/(?<=^|[\s;,])\!\[[^\v[\]]*\]\((?<url>https?\:\/\/[^\s()]+?\.(?:png|jpeg|jpg|gif))\)(?=$|[\s.!?;,])/ui' ; return $ url = $ markdown && preg_match ( $ regex , $ markdown , $ _m ) ? $ _m [ 'url' ] : '' ; }
First image URL.

@since 170124.74961 Initial release.

@param string $markdown Markdown.

@return string First image URL.
First image URL .