<?php

$str = <<<STR
    ...
    ...
    var strings = ["aaa","bbb","ccc","ddd","eee"];
    ...
    ...
STR;

preg_match_all('/(?:\bvar\s+strings\s*=\s*\[|\G,)\s*"([^"]*)"/',$str,$matches);
print_r($matches[1]);


?>