fix: add missing getNativeScrollRef type for ScrollView

[zbauman3]

Summary:

The Problem

When trying to measure the location of a View within a ScrollView (ie. for scrolling to the view), the current recommended method is to use measureLayout on the nested view to determine its location inside the containing scroll view:

const MyComponent = () => {
  const scrollViewRef = useRef<ScrollView>(null);
  const nestedViewRef = useRef<View>(null);

  const scrollToNestedView = () => {
    if (!scrollViewRef.current || !nestedViewRef.current) {
      return;
    }

    nestedViewRef.current.measureLayout(
      scrollViewRef.current.getInnerViewNode(),
      (x, y) => { scrollViewRef.current.scrollTo({ y, animated: true }); },
    );
  }

  return (
    <ScrollView ref={scrollViewRef}>
      <View ref={nestedViewRef}>
        { /* content */ }
      </View>
    </ScrollView>
  );
}

This is valid in the Typescript types layer. However, the only two methods on ScrollView to use in this scenario that are available in the type definitions are getScrollableNode and getInnerViewNode – both of these methods return a number. The issue is that a number not a valid value to use with measureLayout because its source returns early for that type.

(Note, you can also use findNodeHandle with the scroll view ref, but this also returns a number.)

The Solution

The long-term solution would be to update the types for both measureLayout and ScrollView. However, that would constitute a breaking change and require some fairly expansive updates. Instead, I am proposing an additive solution.

ScrollView has a public method called getNativeScrollRef which returns the underlying HostInstance. This method correctly works in the runtime layer, but is not supported in the types layer. This PR exposes the public method in the type definition so that we can properly access the underlying instance without using @ts-ignore.

Changelog:[GENERAL] [FIXED] - Expose ScrollView.getNativeScrollRef on the type definition to allow accessing the underlying HostInstance.

Test Plan:

None needed. This is only a type update exposing existing functionality.

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[zbauman3]

@rshest or @cortinico, it looks like you two have done some previous reviewing on this file. I would love a review/feedback if either of you have time.

TYIA! 🙏

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

[facebook-github-bot]

@rshest merged this pull request in 4b91b63.

[react-native-bot]

This pull request was successfully merged by @zbauman3 in 4b91b63

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