Flatten workspace (#120)

packages/react/src/utils/use-composed-refs.ts

@@ -0,0 +1,60 @@
+import * as React from 'react';
+
+type PossibleRef<T> = React.Ref<T> | undefined;
+
+/**
+ * Set a given ref to a given value
+ * This utility takes care of different types of refs: callback refs and RefObject(s)
+ */
+function setRef<T>(ref: PossibleRef<T>, value: T): (() => void) | void | undefined {
+  if (typeof ref === 'function') {
+    return ref(value);
+  } else if (ref !== null && ref !== undefined) {
+    (ref as React.MutableRefObject<T>).current = value;
+  }
+}
+
+/**
+ * A utility to compose multiple refs together
+ * Accepts callback refs and RefObject(s)
+ */
+function composeRefs<T>(...refs: PossibleRef<T>[]): React.RefCallback<T> {
+  return (node) => {
+    let hasCleanup = false;
+    const cleanups = refs.map((ref) => {
+      const cleanup = setRef(ref, node);
+      if (!hasCleanup && typeof cleanup == 'function') {
+        hasCleanup = true;
+      }
+      return cleanup;
+    });
+
+    // React <19 will log an error to the console if a callback ref returns a
+    // value. We don't use ref cleanups internally so this will only happen if a
+    // user's ref callback returns a value, which we only expect if they are
+    // using the cleanup functionality added in React 19.
+    if (hasCleanup) {
+      return () => {
+        for (let i = 0; i < cleanups.length; i++) {
+          const cleanup = cleanups[i];
+          if (typeof cleanup == 'function') {
+            cleanup();
+          } else {
+            setRef(refs[i], null);
+          }
+        }
+      };
+    }
+  };
+}
+
+/**
+ * A custom hook that composes multiple refs
+ * Accepts callback refs and RefObject(s)
+ */
+function useComposedRefs<T>(...refs: PossibleRef<T>[]): React.RefCallback<T> {
+  // eslint-disable-next-line react-hooks/exhaustive-deps
+  return React.useCallback(composeRefs(...refs), refs);
+}
+
+export { composeRefs, useComposedRefs };