Split up monolith index.js into multiple files

js/EventBus.js

@@ -0,0 +1,44 @@
+/**
+ * A simple publish-subscribe event bus for decoupled communication between components.
+ * @class EventBus
+ */
+export class EventBus {
+    constructor() {
+        /** @type {Object.<string, Function[]>} */
+        this.events = {};
+    }
+
+    /**
+     * Subscribe to an event.
+     * @param {string} event - The event name to subscribe to.
+     * @param {Function} callback - The callback function to execute when the event is emitted.
+     * @returns {Function} An unsubscribe function that removes this listener.
+     */
+    on(event, callback) {
+        if (!this.events[event]) {
+            this.events[event] = [];
+        }
+        this.events[event].push(callback);
+        return () => this.off(event, callback);
+    }
+
+    /**
+     * Unsubscribe from an event.
+     * @param {string} event - The event name to unsubscribe from.
+     * @param {Function} callback - The callback function to remove.
+     */
+    off(event, callback) {
+        if (!this.events[event]) return;
+        this.events[event] = this.events[event].filter(cb => cb !== callback);
+    }
+
+    /**
+     * Emit an event to all subscribers.
+     * @param {string} event - The event name to emit.
+     * @param {*} data - The data to pass to all subscribers.
+     */
+    emit(event, data) {
+        if (!this.events[event]) return;
+        this.events[event].forEach(callback => callback(data));
+    }
+}