$strOutput =~ s{ # First, we'll list things we want # to match, but not throw away ( # Match a regular expression (they start with ( or =). # Then the have a slash, and end with a slash. # The first slash must not be followed by * and cannot contain # newline chars. eg: var "re = /\*/;" or "a = b.match (/x/);" (?: [\(=] \s* / (?: # char class contents \[ \^? ]? (?: [^]\\]+ | \\. )* ] | # escaped and regular chars (\/ and \.) (?: [^[\\\/]+ | \\. )* )* /[gi]* ) | # or double quoted string (?: "[^"\\]* (?:\\.[^"\\]*)*" [^"'/]* )+ | # or single quoted constant (?: '[^'\\]* (?:\\.[^'\\]*)*' [^"'/]* )+ ) | # or we'll match a comment. Since it's not in the # $1 parentheses above, the comments will disappear # when we use $1 as the replacement text. / # (all comments start with a slash) (?: # traditional C comments (?: \* [^*]* \*+ (?: [^/*] [^*]* \*+ )* / ) | # or C++ //-style comments (?: / [^\n]* ) ) }{$1}gsx;