@typescript-eslint/no-magic-numbers applies to types

[Guillaume-Docquier]

Hello! I'm trying out eslint-config-love and I'm facing issues with @typescript-eslint/no-magic-numbers

Consider the following code:

export type Rating = 1 | 2 | 3 | 4 | 5;

@typescript-eslint/no-magic-numbers complains...
I like the spirit of the rule, but to me export type Rating would be the equivalent of const SOMETHING = 9000 in type land.
Would you consider ignoreNumericLiteralTypes?

[mightyiam]

Thank you for bringing this up, @Guillaume-Docquier . I am hereby considering. Say, is there an alternative other than ignoring the rule for the line?

[Guillaume-Docquier]

I could use an enum.
It would work for me in this case, but I can see cases where it wouldn't make sense (and a lot of people don't like TS enums).

enum Rating {
  VERY_BAD = 1,
  BAD = 2,
  AVERAGE = 3,
  GOOD = 4,
  VERY_GOOD = 5,
}

Or I could derive the type from a constant, but I think it looks silly and it produces another error.

const AVERAGE = 3; // ESLint: 'AVERAGE' is assigned a value but only used as a type.(@typescript-eslint/no-unused-vars)
export type Rating = 1 | 2 | typeof AVERAGE | 4 | 5;

[mightyiam]

The enum labels the numbers, preventing them from being magic numbers. Seems like a straightforward choice to me, in lieu of edge cases where enums are undesirable. What do you think?

[Guillaume-Docquier]

It works in some cases, but not all.
For example DayOfTheMonth, which I have in this codebase, makes little sense in enum form.

Or anything that is quantity based won't play well with enums because you'll end up doing ONE = 1, TWO = 2, etc.

I ended up reconfiguring this rule because I use type litterals a lot to restrict number ranges when I can and enums are not always suitable.