[GENERAL] [FIXED] VirtualizedList/FlatList: Stricter typing for onViewableItemsChanged

[miallo]

Summary:

The previous typing of FlatList and VirtualizedList did not convey any information on the type of the items passed in to onViewableItemsChanged, but instead the type was set to any. This PR adds the type information.

I set a default type any for thy ViewToken, because the type is exported and not having it would be a breaking change if that type is used. Like this it gracefully falls back to the default behavior of the any type.

Notice: I don't know how typing in "flow" works, but the same "issue" seems to be in there as well. Maybe someone with more flow experience can fix that as well:

react-native/packages/virtualized-lists/Lists/ViewabilityHelper.js

Lines 19 to 20 in ae42e02

	export type ViewToken = {
	item: any,

Changelog:

[GENERAL] [FIXED] - Add type information for items of VirtualizedList in onViewableItemsChanged signature
[GENERAL] [FIXED] - Add type information for items of FlatList in onViewableItemsChanged signature

Test Plan:

Without the changes, typecheck of the project was fine, but with the changes applied to the node_modules/react-native copy a type error was found:

$ npm run typecheck

> my-project@1.0.0 typecheck
> tsc --skipLibCheck

src/MyComponent.tsx:385:29 - error TS2345: Argument of type '(string | number)[]' is not assignable to parameter of type 'number[]'.
  Type 'string | number' is not assignable to type 'number'.
    Type 'string' is not assignable to type 'number'.

385                             viewableItems
                                ~~~~~~~~~~~~~
386                                 .filter(
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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@NickGerleman has imported this pull request. If you are a Meta employee, you can view this diff on Phabricator.

[facebook-github-bot]

@NickGerleman merged this pull request in 35f5c3a.