feat: implemented an event manager

frontend/src/lib/event-manager/event-manager.js

@@ -0,0 +1,65 @@
+
+export const EVENT_TYPE = {
+    CLICK : 'click',
+    KEYDOWN : 'keydown',
+    //more to be added
+};
+
+
+
+export class EventManager {
+    _registeredListeners;
+
+
+    constructor() {
+        this._registeredListeners = [];
+    }
+
+    registerNewListener(eventWrapper) {
+        this._debugLog('registerNewListener', eventWrapper);
+        let element = eventWrapper.element;
+        element.addEventListener(eventWrapper.eventType, eventWrapper.eventHandler);
+        this._registeredListeners.push(eventWrapper);
+    }
+
+    removeAllEventListenersFromUtil() {
+        this._debugLog('removeAllEventListenersFromUtil',);
+        for (let eventWrapper of this._registeredListeners) {
+            let element = eventWrapper.element;
+            element.removeEventListener(eventWrapper.eventType, eventWrapper.eventHandler);
+        }
+        this._registeredListeners = [];        
+    }
+
+    //_debugLog() {}
+    _debugLog(fName, ...args) {
+      console.log(`[DEBUGLOG] EventManager.${fName}`, { args: args, instance: this });
+    }
+}
+
+export class EventWrapper {
+    _eventType;
+    _eventHandler;
+    _element;
+
+    constructor(_eventType, _eventHandler, _element) {
+        if(!_eventType || !_eventHandler || !_element) {
+            throw new Error('Not enough arguments!');
+        }
+        this._eventType = _eventType;
+        this._eventHandler = _eventHandler;
+        this._element = _element;
+    }
+
+    get eventType() {
+        return this._eventType;
+    }
+
+    get eventHandler() {
+        return this._eventHandler;
+    }
+
+    get element() {
+        return this._element;
+    }
+}