`no-magic-numbers`: allow numbers in expressions

Now the rule forbids usage of numbers even when they construct a constant with some expression. F.ex., if we want to correctly set a 2-min timeout value we’ll write something like below getting rule report

const MSEC_PER_SEC = 1000;
const SEC_PER_MIN = 60;
...
const INTRV = 2 * SEC_PER_MIN * MSEC_PER_SEC; // rule complains

What rule do you want to change? no-magic-numbers

Does this change cause the rule to produce more or fewer warnings? fewer

How will the change be implemented? (New option, new default behavior, etc.)? new default behavior

Please provide some example code that this change will affect:

const FOO = 2;
const BAR = 3 * FOO;

What does the rule currently do for this code? 2:13 No magic number 3

What will the rule do after it’s changed? no message

Are you willing to submit a pull request to implement this change? Probably, if the team accepts the request

[kaicataldo]

I agree with @anikethsaha that this is exactly what the rule is intended to enforce. In this specific example the 2 doesn’t seem like a magic number because it’s fairly clear what this it’s referring to, but if it were a larger number it would be confusing. For instance, if the code snippet looked like this, I think the rule should warn:

const MSEC_PER_SEC = 1000;
const SEC_PER_MIN = 60;
...
const INTRV = 8768652 * SEC_PER_MIN * MSEC_PER_SEC;

Given the above, I’m not sure how the rule would be able to distinguish when a magic number is allowed in an expression and when it isn’t, and should treat all numbers in expressions as magic numbers.

[kaicataldo]

The team has made the difficult decision to freeze stylistic rules (please see https://eslint.org/blog/2020/05/changes-to-rules-policies for more details), and we unfortunately won’t be able to accept this proposal.

Thanks for contributing to ESLint and for being willing to implement your proposal.