Type Redux store and middleware (#24843)

app/javascript/mastodon/store/middlewares/sounds.ts

@@ -0,0 +1,56 @@
+import { Middleware, AnyAction } from 'redux';
+import { RootState } from '..';
+
+interface AudioSource {
+  src: string
+  type: string
+}
+
+const createAudio = (sources: AudioSource[]) => {
+  const audio = new Audio();
+  sources.forEach(({ type, src }) => {
+    const source = document.createElement('source');
+    source.type = type;
+    source.src = src;
+    audio.appendChild(source);
+  });
+  return audio;
+};
+
+const play = (audio: HTMLAudioElement) => {
+  if (!audio.paused) {
+    audio.pause();
+    if (typeof audio.fastSeek === 'function') {
+      audio.fastSeek(0);
+    } else {
+      audio.currentTime = 0;
+    }
+  }
+
+  audio.play();
+};
+
+export  const soundsMiddleware = (): Middleware<Record<string, never>, RootState> => {
+  const soundCache: {[key: string]: HTMLAudioElement} = {
+    boop: createAudio([
+      {
+        src: '/sounds/boop.ogg',
+        type: 'audio/ogg',
+      },
+      {
+        src: '/sounds/boop.mp3',
+        type: 'audio/mpeg',
+      },
+    ]),
+  };
+
+  return () => next => (action: AnyAction) => {
+    const sound = action?.meta?.sound;
+
+    if (sound && soundCache[sound]) {
+      play(soundCache[sound]);
+    }
+
+    return next(action);
+  };
+};