Don't use a single regex. Have a regex for each type of item and parse them out as you go (stealing from myself):

while(  $code !~ m#\G$#gc  ) {
    if(  $code =~ m#\G//(.*)\n#gc  ) {
        # $1 is end-of-line comment
    } elsif(  $code =~ m#\G"((?:[^"\\]|\\.)*)"#gc  ) {
        # $1 is the inside double quotes
    } elsif(  $code =~ m#\G'((?:[^'\\]|\\.)*)'#gc  ) {
        # $1 is the inside single quotes
    } elsif(  $code =~ m#\G/*(.?)*/#gmc  ) {
        # $1 is a comment
    } elsif(  $code =~ m#\G/((?:[^/\\]|\\.)*)/#gc  ) {
        # $1 is a regex
    } elsif(  $code =~ m#\G([^/'"]+)#gc  ) {
        # $1 is "other code"
    } elsif(  $code =~ m#\G/#gc  ) {
        # division, we hope.
    } else {
        # We have hit invalid code?
    }
}
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But this can still be fooled, though it is much harder. (:

Update: The only real problem (based on some guesses since I don't know JavaScript syntax) is determining whether a / is starting a regex or is denoting division (I'm assuming that "//" isn't a valid regex and is always an end-of-line comment). This is similar to the problem with parsing Perl, knowing whether the next thing is supposed to be a term or an operator. Perl makes this extra hard because function prototypes can change whether the parser expects a term or operator to follow that function invocation. I doubt JavaScript makes things that hard so someone who understands the syntax could probably fix up my code to work 100% of the time.

To go beyond this, I'd probably start looking into Parse::RecDescent.

        - tye (but my friends call me "Tye")