meliorence / meliorence/react-native-snap-carousel

useRef with TypeScript

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Description

Is this a bug report, a feature request, or a question?

Bug report.

Have you followed the required steps before opening a bug report?
Have you made sure that it wasn't a React Native bug?

Yes

Is the bug specific to iOS or Android? Or can it be reproduced on both platforms?

TypeScript related.

Is the bug reproductible in a production environment (not a debug one)?

Yes

Environment
info Fetching system and libraries information...
System:
    OS: macOS 10.15.5
    CPU: (16) x64 AMD Ryzen 7 1700X Eight-Core Processor         
    Memory: 166.43 MB / 16.00 GB
    Shell: 5.7.1 - /bin/zsh
  Binaries:
    Node: 12.18.0 - ~/.nvm/versions/node/v12.18.0/bin/node
    Yarn: 1.22.4 - ~/.nvm/versions/node/v12.18.0/bin/yarn
    npm: 6.14.4 - ~/.nvm/versions/node/v12.18.0/bin/npm
  SDKs:
    iOS SDK:
      Platforms: iOS 13.5, DriverKit 19.0, macOS 10.15, tvOS 13.4, watchOS 6.2
  IDEs:
    Xcode: 11.5/11E608c - /usr/bin/xcodebuild
  npmPackages:
    react: 16.13.1 => 16.13.1 
    react-native: https://github.com/expo/react-native/archive/sdk-37.0.0.tar.gz => 0.61.4
Expected Behavior

That TypeScript does not error when using useRef.

Actual Behavior

TypeScript warns that refs are not compatible.

Steps to Reproduce
const carouselRef = useRef<Carousel<Item>>(null)

<Carousel ref={carouselRef} />

Will error:

No overload matches this call.
  Overload 1 of 2, '(props: Readonly<CarouselProperties<Item>>): Carousel<Item>', gave the following error.
    Type 'MutableRefObject<Carousel<Item>>' is not assignable to type 'string | (string & ((instance: ScrollViewProps) => void)) | (string & RefObject<ScrollViewProps>) | (string & ((instance: CarouselStatic<Item>) => void)) | ... 22 more ... | (RefObject<...> & ... 1 more ... & RefObject<...>)'.
      Type 'MutableRefObject<Carousel<Item>>' is not assignable to type 'React.RefObject<...> & React.RefObject<...> & React.RefObject<...>'.
        Type 'MutableRefObject<Carousel<Item>>' is not assignable to type 'RefObject<CarouselStatic<Item>>'.
          Types of property 'current' are incompatible.
            Type 'Carousel<Item>' is missing the following properties from type 'CarouselStatic<Item>': currentIndex, currentScrollPosition, startAutoplay, stopAutoplay, and 4 more.
  Overload 2 of 2, '(props: CarouselProperties<Item>, context?: any): Carousel<Item>', gave the following error.
    Type 'MutableRefObject<Carousel<Item>>' is not assignable to type 'string | (string & ((instance: ScrollViewProps) => void)) | (string & RefObject<ScrollViewProps>) | (string & ((instance: CarouselStatic<Item>) => void)) | ... 22 more ... | (RefObject<...> & ... 1 more ... & RefObject<...>)'.
      Type 'MutableRefObject<Carousel<Item>>' is not assignable to type 'React.RefObject<...> & React.RefObject<...> & React.RefObject<...>'.
        Type 'MutableRefObject<Carousel<Item>>' is not assignable to type 'RefObject<CarouselStatic<Item>>'.

I also tried typing the useRef with CarouselStatic but this didn't help.

I see that I can also do:

<Carousel ref={(ref) => (carouselRef.current = ref)} />

Although I am not sure the typings are correct?

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by reproducing the useRef snippet from the issue against the package's TypeScript declarations, then inspect the Carousel ref typing implicated by the compiler error. Done means a correctly typed useRef can be passed to Carousel without the reported overload or ref incompatibility errors.

Written by the indexing model from the issue text.

Assessment

Tech stack
react-native, typescript
Domain
mobile-dev
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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