$re = '/{[^)]+/';
$str = 'var block = new MatchesBlock(\'page_competition_1_block_competition_matches_summary_5\', \'block_competition_matches_summary\', {"page":0,"bookmaker_urls":{"13":[{"link":"http:\\/\\/www.bet365.com\\/home\\/?affiliate=365_178981","name":"Bet 365"}]},"block_service_id":"competition_summary_block_competitionmatchessummary","round_id":42011,"outgroup":false,"view":2,"competition_id":13});';
preg_match($re, $str, $matches, PREG_OFFSET_CAPTURE, 0);
// Print the entire match result
var_dump($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