Corrected typing for RangerModifier

[joebenn]

Came across a typing issue when using react-day-picker in our Typescript project.

Specifically, making use of the util function addDayToRange. The typing for addDayToRange is defined as:
addDayToRange(day: Date, range: RangeModifier): RangeModifier;.
where export interface RangeModifier { from: Date; to: Date; }

However the function addDayToRange, implemented in DateUtils.jsexpects (and handles) null date objects (from and to) objects, which contradicts the current typing for RangeModifier

I simply changed the typing to allow for the dates to be undefined within the RangeModifier object, and this solved the typing issues we were experiencing.

I also noticed RangeModifier was defined twice, so I removed the duplicate.

Cheers!

[elvorad]

I have the same TypeScript issue and would like to use the change that joebenn has requested – thank you for reaching in this merge request, joebenn! Dear maintainers, would somebody of you please be so kind as to approve this merge request and release a new version?

The tutorial site found under http://react-day-picker.js.org/examples/selected-range has an example in which from and to are set to undefined, yet the current type definition does not support this use case and throws false positives.

[mhaidamashko]

If you want set undefined to interface property better to use ? if it's possible.

export interface RangeModifier {
  from?: Date;
  to?: Date;
}

Nevertheless, I think there should be

export interface RangeModifier {
  from?: Date | null;
  to?: Date | null;
}

Because In realisation of the function addDayToRange it has fallback to nulls.

export function addDayToRange(day, range = { from: null, to: null }) {}