Disable animations for users that prefer reduced motion

src/usePrefersReducedMotion.ts

@@ -0,0 +1,42 @@
+/*
+Copyright 2022 New Vector Ltd
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+import { useCallback, useRef, useState } from "react";
+
+import { useEventTarget } from "./useEvents";
+
+/**
+ * @returns Whether the user has requested reduced motion.
+ */
+export const usePrefersReducedMotion = () => {
+  const mediaQuery = useRef<MediaQueryList>();
+  if (mediaQuery.current === undefined)
+    mediaQuery.current = matchMedia("(prefers-reduced-motion)");
+
+  const [prefersReducedMotion, setPrefersReducedMotion] = useState(
+    mediaQuery.current.matches
+  );
+  useEventTarget(
+    mediaQuery.current!,
+    "change",
+    useCallback(
+      () => setPrefersReducedMotion(mediaQuery.current!.matches),
+      [setPrefersReducedMotion]
+    )
+  );
+
+  return prefersReducedMotion;
+};