正则表达式：跳过引号中的注释

Question

With this regex /#(.*?)\\r?\\n|#(.*?)$/g am able to parse the content below but it also matches the comment within the quotes.

How do I avoid this?

#
# this is a comment
#

but this is '# not a comment'
and this is "# not a comment either"

# help, please

I tried /(?!\\B["'][^']*)(#(.*?)\\r?\\n|#(.*?)$)(?![^']*['"]\\B)/g but the results are buggy.

Any help?

Answer 1

Try this simple code to match a comment only at the beginning of a line

/^#(.*?)$/gm

Demo: https://regex101.com/r/YngpW9/1/

Alternative code to match the comment anywhere

/^[^'"]*?(#.*?)$/gm

Demo: https://regex101.com/r/YngpW9/2/

Make sure to use gm , not just g , so that you can make use of ^ which matches the beginning of a line.

This is an example

 var string = ` # # this is a comment # but this is '# not a comment' and this is "# not a comment either" # help, please `; var regex = /^[^'"]*?(#.*?)$/gm; var match = regex.exec(string); while (match != null) { document.write(match[1]+'<br>') match = regex.exec(string); } 

Answer 2

One way to accomplish this is to use capture groups and alternation to distinguish between the contexts you want, and the contexts you don't want. This is a technique I learned from this article .

The trick is to only put the thing you want to match in a capture group, and leave all other alternatives out of the capture group. Then you will filter your result matches based on whether or not they have a capture group.

The regex would look like this:

/'(?:\\.|.)*?'|"(?:\\.|.)*?"|#(.*)$/gm

Regex101 Demo

You would use it like this:

 var re = /'(?:\\\\.|.)*?'|"(?:\\\\.|.)*?"|#(.*)$/gm; var str = ` # # this is a comment # but this is '# not a comment' and this is "# not a comment either" # help, please `; str.replace(re, function(match, group1) { if (group1 !== undefined) { console.log(match); } }); 

You can even extend this to match multi-line comments .

 var re = /'(?:\\\\.|.)*?'|"(?:\\\\.|.)*?"|(#(.*)$|\\/\\*([\\s\\S]*?)\\*\\/)/gm; var str = ` # # this is a comment # /* this is a multiline comment */ but this is '# not a comment' and this is "# not /* a comment */ either" # help, please `; str.replace(re, function(match, group1) { if (group1 !== undefined) { console.log(match); } });