Enforce use of non-strict equality (`==`/`!=`) when comparing to `null`

Right now I use eqeqeq to enforce strict (===) equality everywhere, except when comparing to null. That is great, but I actually want to go one step further and enforce non-strict (==) equality when comparing any value to null literal.

To put it another way, this will NOT currently throw any lint warning:

let foo;
console.log('is it null', foo == null);
console.log('is it really null', foo === null);

Those two statements are not easy to tell apart during code review. The issue can arise that a coder will use strict equality out of habit yet (in our codebase) they should always use loose equality when comparing to null in order to also catch undefined. Similar code will pass lint and pass tests and then later it might fail in production when undefined sneaks in somehow. I’d like to statically enforce loose equality for null.

Would you be open to a PR?

[nzakas]

I don’t think we should use “eqeq” in option names as it’s the opposite of the rule. “always” , “never”, etc. Should mean “always use ===” and “never use ===”.

It might be easiest to deprecate allow-null in favor of an options object:

eqeqeq: [error, always, {
    null: always | never | ignore
}]

Where “ignore” is equivalent to allow-null

[btmills]

@sstur Just checking in, how are things coming along? Is there anything I can do to help?