$re = '/var (?:(?!var).)*?=function.*11/';
$str = 'var abc1=function(_x1,_y1){var a=1,b=2,c=3};var abc2=function(_x2,_y2){var a=4,b=5,c=6};var abc3=function(_x3,_y3){var a=7,b=8,c=9};var abc4=function(_x4,_y4){var a=10,b=11,c=12};var abc5=function(_x5,_y5){var a=13,b=14,c=15}';
preg_match_all($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