feat(utils): add getChildRef (#109)

Author: kyletsang

src/useRTGTransitionProps.ts

@@ -4,7 +4,7 @@ import {
   TransitionProps as RTGTransitionProps,
   TransitionStatus,
 } from 'react-transition-group/Transition';
-import { getReactVersion } from './utils';
+import { getChildRef } from './utils';
 
 export type TransitionProps = RTGTransitionProps & {
   children:
@@ -33,15 +33,8 @@ export default function useRTGTransitionProps({
   children,
   ...props
 }: TransitionProps) {
-  const { major } = getReactVersion();
-  const childRef =
-    major >= 19 ? (children as any).props.ref : (children as any).ref;
-
   const nodeRef = useRef<HTMLElement>(null);
-  const mergedRef = useMergedRefs(
-    nodeRef,
-    typeof children === 'function' ? null : childRef,
-  );
+  const mergedRef = useMergedRefs(nodeRef, getChildRef(children));
 
   const normalize =
     (callback?: (node: HTMLElement, param: any) => void) => (param: any) => {

src/utils.ts

@@ -12,3 +12,14 @@ export function getReactVersion() {
     patch: +parts[2],
   };
 }
+
+export function getChildRef(
+  element?: React.ReactElement | ((...args: any[]) => React.ReactNode) | null,
+) {
+  if (!element || typeof element === 'function') {
+    return null;
+  }
+  const { major } = getReactVersion();
+  const childRef = major >= 19 ? element.props.ref : (element as any).ref;
+  return childRef;
+}

test/utilsSpec.tsx

@@ -0,0 +1,18 @@
+import { describe, expect, it } from 'vitest';
+import { getChildRef } from '../src/utils';
+
+describe('utils', () => {
+  describe('getChildRef', () => {
+    it('should return null if ref is null', () => {
+      expect(getChildRef(null)).to.equal(null);
+    });
+
+    it('should return null if ref is undefined', () => {
+      expect(getChildRef(undefined)).to.equal(null);
+    });
+
+    it('should return null if ref is a function', () => {
+      expect(getChildRef(() => null)).to.equal(null);
+    });
+  });
+});