events: support dispatching event from event

Co-authored-by: Benjamin Gruenbaum <[email protected]>

PR-URL: #34015
Reviewed-By: Denys Otrishko <[email protected]>
Reviewed-By: Benjamin Gruenbaum <[email protected]>

Author: jasnell

lib/internal/event_target.js

@@ -7,7 +7,6 @@ const {
   Map,
   NumberIsInteger,
   Object,
-  Set,
   Symbol,
   SymbolFor,
   SymbolToStringTag,
@@ -199,7 +198,6 @@ class EventTarget {
   static [kIsEventTarget] = true;
 
   [kEvents] = new Map();
-  #emitting = new Set();
 
   [kNewListener](size, type, listener, once, capture, passive) {}
   [kRemoveListener](size, type, listener, capture) {}
@@ -266,25 +264,20 @@ class EventTarget {
   }
 
   dispatchEvent(event) {
-    if (!(event instanceof Event)) {
+    if (!(event instanceof Event))
       throw new ERR_INVALID_ARG_TYPE('event', 'Event', event);
-    }
 
-    if (!isEventTarget(this)) {
+    if (!isEventTarget(this))
       throw new ERR_INVALID_THIS('EventTarget');
-    }
 
-    if (this.#emitting.has(event.type) ||
-        event[kTarget] !== null) {
+    if (event[kTarget] !== null)
       throw new ERR_EVENT_RECURSION(event.type);
-    }
 
     const root = this[kEvents].get(event.type);
     if (root === undefined || root.next === undefined)
       return true;
 
     event[kTarget] = this;
-    this.#emitting.add(event.type);
 
     let handler = root.next;
     let next;
@@ -310,7 +303,6 @@ class EventTarget {
       handler = next;
     }
 
-    this.#emitting.delete(event.type);
     event[kTarget] = undefined;
 
     return event.defaultPrevented !== true;

test/parallel/test-eventtarget.js

@@ -293,13 +293,12 @@ ok(EventTarget);
 
   // Once handler only invoked once
   const ev = common.mustCall((event) => {
-    throws(() => eventTarget.dispatchEvent(new Event('foo')), {
-      code: 'ERR_EVENT_RECURSION'
-    });
+    // Can invoke the same event name recursively
+    eventTarget.dispatchEvent(new Event('foo'));
   });
 
   // Errors in a handler won't stop calling the others.
-  eventTarget.addEventListener('foo', ev);
+  eventTarget.addEventListener('foo', ev, { once: true });
 
   eventTarget.dispatchEvent(new Event('foo'));
 }