<?php
$str = <<<STR
...
...
var strings = ["aaa","bbb","ccc","ddd","eee"];
...
...
STR;
preg_match_all('/(?:\bvar\s+strings\s*=\s*\[|\G,)\s*"([^"]*)"/',$str,$matches);
?>
PD9waHAKCiRzdHIgPSA8PDxTVFIKICAgIC4uLgogICAgLi4uCiAgICB2YXIgc3RyaW5ncyA9IFsiYWFhIiwiYmJiIiwiY2NjIiwiZGRkIiwiZWVlIl07CiAgICAuLi4KICAgIC4uLgpTVFI7CgpwcmVnX21hdGNoX2FsbCgnLyg/OlxidmFyXHMrc3RyaW5nc1xzKj1ccypcW3xcRywpXHMqIihbXiJdKikiLycsJHN0ciwkbWF0Y2hlcyk7CnByaW50X3IoJG1hdGNoZXNbMV0pOwoKCj8+