add events support

frontend/src/modules/Gefest/element.ts

@@ -2,6 +2,7 @@ import { GefestEngine } from './engine';
 import { GefestStyle } from './style';
 
 // The general class of Gefest
+type gefestElementEvents = "onClick";
 export abstract class GefestElement {
     style: GefestStyle | null = null;
     isHidden: boolean = false;
@@ -10,9 +11,16 @@ export abstract class GefestElement {
     protected content: (GefestElement | string)[] | string;
     protected attributes: Record<string, string> = {};
     protected classList: Set<string> = new Set();
+    //protected eventHandlers: Record<string, (eventType: string, eventData: unknown) => void> = {};
+    protected eventHandlers: ((eventType: string, eventData: unknown) => void)[] = [];
 
     protected clickHandler: (() => void) | null = null;
 
+    emit(event: gefestElementEvents, data: unknown = undefined) {
+        for (let handler of this.eventHandlers)
+            new Promise((rs) => rs(handler("onClick", data)));
+    }
+
     set onClick(handler: (() => void) | null) {
         if (handler) {
             this.clickHandler = handler;
@@ -26,6 +34,8 @@ export abstract class GefestElement {
             return null;
         return () => {
             this.clickHandler!();
+            this.emit("onClick");
+            
             GefestEngine.activateOnClick();
         };
     }