setup audio receiver and event dispatcher

Dispatcher.js

@@ -0,0 +1,45 @@
+class Dispatcher {
+  constructor(domain, allowedEvents=[]) {
+    this.LISTENERS = {};
+    this.allowedEvents = allowedEvents;
+    this.domain = domain;
+  }
+  emit = (eventName, ...args) => {
+    // console.log(`${this.domain}.${eventName}`, ...args);
+    if(!this.LISTENERS[eventName]) return;
+    this.LISTENERS[eventName].forEach(callback => callback(...args));
+  }
+  addListener = (eventName, callback) => {
+    if(this.allowedEvents.length !== 0) {
+      if(!this.allowedEvents.includes(eventName)) {
+        throw new Error(`Event "${eventName}" is not allowed for ${this.domain}.`)
+      }
+    }
+    if(typeof callback !== 'function')
+        throw new Error('Must provide a function');
+
+    if(!this.LISTENERS[eventName]) {
+      this.LISTENERS[eventName] = [];
+    }
+    if(this.LISTENERS[eventName].includes(callback)) return;
+    this.LISTENERS[eventName].push(callback);
+  }
+  removeListener = (eventName, callback) => {
+    if(!this.LISTENERS[eventName]) return;
+    const i = this.LISTENERS[eventName].indexOf(callback);
+    if(i === -1) return;
+    this.LISTENERS[eventName].splice(i, 1);
+  }
+  clearEventListeners = eventName => {
+    if(!this.LISTENERS[eventName]) return;
+    delete this.LISTENERS[eventName];
+  }
+  clearAllEventListeners = () => {
+    Object
+      .keys(this.LISTENERS)
+      .forEach(
+        eventName => this.clearEventListeners(eventName)
+      );
+  }
+}
+export default Dispatcher;