Make months and weekdays types slightly less restrictive

[johnjesse]

I think the typings for months, weekdaysLong and weekdaysShort are too strict. For instance, I get a type error from the following

const months = ['J', 'F', 'M', 'A', 'M', 'J', 'J', 'A', 'S', 'O', 'N', 'D'];

<DayPicker
  months={months}
  ...
/>

because the inferred type of the months variable is string[]. Whilst the current typings for months, weekdaysLong and weekdaysShort are strictly true in requiring 12, 7 and 7 entries, typescript has difficulty in inferring those types and this makes them unwieldy to use in practice. I suggest loosening them slightly to be sting[].

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[codecov]

Codecov Report

Merging #843 into master will not change coverage.
The diff coverage is n/a.

@@          Coverage Diff          @@
##           master   #843   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files          15     15           
  Lines         645    645           
  Branches      141    141           
=====================================
  Hits          645    645

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[giladgray]

type aliases would solve this. if you could say

import { MonthsArray, DaysArray } from "react-day-picker";

const months: MonthsArray = [ ...12 type-safe strings ];
const weekdaysLong: DaysArray = [ ...7 type-safe strings ];

[johnjesse]

I hadn't thought about exposing the type aliases.

It's still a bit annoying to have to explicitly declare the type or cast them though. Incidentally that's currently how I get around the problem - by declaring my own MonthNames, and DayNames types and casting.

Playing around with it, it gives better type safety to this case (ts-playground)

Personally I don't think it gives you very much in this instance, If I'm getting the month names from something else, like moment, I have to then cast anyway. (Or convince whatever 3rd party source I'm using to use the same typing convention).

[sokmeann]

@johnjesse any updates on this PR? it is holding up another PR I made to blueprintjs about a month ago... Would need that merged sooner rather than later as I am using the component for an app that needs to go to production :(

@giladgray

[johnjesse]

@sokmeann no updates I'm afraid, I'm not a maintainer of this library
There hasn't been an update on this repo since September so I'm not sure it's still being maintained.

As a workaround I suggest you type you extract a type

type Months = [string, string, string, string, string, string, string, string, string, string, string, string]
and declare your months as
const months: Months = ['J', ......]

or the same for weekdays

[gpbl]

Hey friends, sorry for being inactive the last months. Just trying to catch it up :)

[johnjesse]

Awesome 😄 thank you!