max-len to ignore Regular Expressions

[joezimjs]

Is there a way to add an option to ignore regular expressions that are too long? Sometimes those things can get huge. For example, URI.js needs a very long regex to parse a URL: https://github.com/medialize/URI.js/blob/gh-pages/src/URI.js#L207

[eslintbot]

Thanks for the issue! We get a lot of issues, so this message is automatically posted to each one to help you check that you've included all of the information we need to help you.

Reporting a bug? Please be sure to include:

1. The version of ESLint you are using (run eslint -v)
2. The source code that caused the problem
3. The configuration you're using (for the rule or your entire config file)
4. The actual ESLint output complete with line numbers

Requesting a new rule? Please be sure to include:

1. The use case for the rule - what is it trying to prevent or flag?
2. Whether the rule is trying to prevent an error or is purely stylistic
3. Why you believe this rule is generic enough to be included

Requesting a feature? Please be sure to include:

1. The problem you want to solve (don't mention the solution)
2. Your take on the correct solution to problem

Including this information in your issue helps us to triage it and get you a response as quickly as possible.

Thanks!

[nzakas]

See the ignorePattern option: http://eslint.org/docs/rules/max-len#options

[bajtos]

@nzakas could you please share an example of the RegExp that describes a line containing regexp definition only, possibly with an assignment to a variable? I think the expression would be pretty complex and thus it may be better to implement his particular exception as a first-class eslint option.

Here is an example of what I would like to achieve:

// assuming max-len 4, these are considered valid:
var foo = /asd/;

foo(
  x,
  /asd/
);

// this is not valid - the comment should be on a different line
var foo = /asd/; /* trailing comment */

// this is not valid - function arguments should be split to multiple lines
foo(x, /asd/);

For example, jscs's maximumLineLength rule has an option regex, which allows regular expression literals to break the rule, see http://jscs.info/rule/maximumLineLength

Thoughts?

[markelog]

It was quite popular option - to ignore regular expression, it was used in jquery preset and other derivates like grunt and wordpress.

In order to increase compatibility with jscs i would like to put this back to agenda and allow myself to reopen this ticket

[nzakas]

@markelog can you explain your proposal?

[markelog]

Sure, regular expression could be very long - like so https://github.com/jquery/jquery/blob/95c7ab68970ce201a2bbff48c8e951d38c228ce8/src/manipulation.js#L32, divide them like new RegExp( '...' + '...' ) wouldn't be ideal but hacky and do the regexp for ignorePattern would much harder then to analyze the ast.

It would be cool if this rule would have an option which would allow to ignore such long regexes, same as maximumLineLength allExcept: ["regex"] option of JSCS

[nzakas]

@markelog sorry, what I meant was, what is your proposal for the new rule option?