ee9.ts

const eventDelegation = {
 map: new Map(),
 init: false,
 supports(eventName: string) {
   return eventName.includes("delegate");
 },
 addEventListener(
   element,
   eventName,
   originalHandler
 ) {
   this.map.set(element, originalHandler);

   if (!this.init) {
     document.addEventListener("click", e => {
       this.map.forEach((handler, element) => {
         if (element.contains(e.target)) {
         // In real-life only the handler should run inside the zone
           handler(e);
         }
       });
     });
     this.init = true;
   }

   return () => {
     this.map.delete(element);
   };
 }
};