From cb3a9ac56c0dbc65b96f3a87d31bdb8d651f97ea Mon Sep 17 00:00:00 2001
From: Benjamin Gruenbaum <benjamingr@gmail.com>
Date: Thu, 28 May 2020 17:33:21 +0300
Subject: [PATCH 1/2] event: cancelBubble is a property

Event#cancelBubble is property (and not a function). Change
Event#cancelBubble to a property and add a test.
---
 lib/internal/event_target.js      | 3 ++-
 test/parallel/test-eventtarget.js | 1 +
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/lib/internal/event_target.js b/lib/internal/event_target.js
index 611aa9922118a1..c2ab97973048e6 100644
--- a/lib/internal/event_target.js
+++ b/lib/internal/event_target.js
@@ -109,7 +109,8 @@ class Event {
   get eventPhase() {
     return this[kTarget] ? 2 : 0;  // Equivalent to AT_TARGET or NONE
   }
-  cancelBubble() {
+  get cancelBubble() { return false; }
+  set cancelBubble() {
     // Non-op in Node.js. Alias for stopPropagation
   }
   stopPropagation() {
diff --git a/test/parallel/test-eventtarget.js b/test/parallel/test-eventtarget.js
index 1b79a6bbb0ffd6..bf6941a2bde35a 100644
--- a/test/parallel/test-eventtarget.js
+++ b/test/parallel/test-eventtarget.js
@@ -35,6 +35,7 @@ ok(EventTarget);
   strictEqual(ev.composed, false);
   strictEqual(ev.isTrusted, false);
   strictEqual(ev.eventPhase, 0);
+  strictEqual(ev.cancelBubble, false);
 
   // Not cancelable
   ev.preventDefault();

From 412d82d273a95ad4bd93f1edcc351a7dbcd61ff4 Mon Sep 17 00:00:00 2001
From: Benjamin Gruenbaum <benjamingr@gmail.com>
Date: Thu, 28 May 2020 17:53:57 +0300
Subject: [PATCH 2/2] fixup! set actual properties

---
 lib/internal/event_target.js      | 14 +++++++++-----
 test/parallel/test-eventtarget.js | 18 ++++++++++++++++++
 2 files changed, 27 insertions(+), 5 deletions(-)

diff --git a/lib/internal/event_target.js b/lib/internal/event_target.js
index c2ab97973048e6..5ece72ea1d9433 100644
--- a/lib/internal/event_target.js
+++ b/lib/internal/event_target.js
@@ -35,12 +35,13 @@ class Event {
   #cancelable = false;
   #timestamp = perf_hooks.performance.now();
 
-  // Neither of these are currently used in the Node.js implementation
+  // None of these are currently used in the Node.js implementation
   // of EventTarget because there is no concept of bubbling or
   // composition. We preserve their values in Event but they are
   // non-ops and do not carry any semantics in Node.js
   #bubbles = false;
   #composed = false;
+  #propagationStopped = false;
 
 
   constructor(type, options) {
@@ -51,6 +52,7 @@ class Event {
     this.#bubbles = !!bubbles;
     this.#composed = !!composed;
     this.#type = `${type}`;
+    this.#propagationStopped = false;
     // isTrusted is special (LegacyUnforgeable)
     Object.defineProperty(this, 'isTrusted', {
       get() { return false; },
@@ -109,12 +111,14 @@ class Event {
   get eventPhase() {
     return this[kTarget] ? 2 : 0;  // Equivalent to AT_TARGET or NONE
   }
-  get cancelBubble() { return false; }
-  set cancelBubble() {
-    // Non-op in Node.js. Alias for stopPropagation
+  get cancelBubble() { return this.#propagationStopped; }
+  set cancelBubble(value) {
+    if (value) {
+      this.stopPropagation();
+    }
   }
   stopPropagation() {
-    // Non-op in Node.js
+    this.#propagationStopped = true;
   }
 
   get [Symbol.toStringTag]() { return 'Event'; }
diff --git a/test/parallel/test-eventtarget.js b/test/parallel/test-eventtarget.js
index bf6941a2bde35a..c0e760d13b1369 100644
--- a/test/parallel/test-eventtarget.js
+++ b/test/parallel/test-eventtarget.js
@@ -41,6 +41,24 @@ ok(EventTarget);
   ev.preventDefault();
   strictEqual(ev.defaultPrevented, false);
 }
+{
+  const ev = new Event('foo');
+  strictEqual(ev.cancelBubble, false);
+  ev.cancelBubble = true;
+  strictEqual(ev.cancelBubble, true);
+}
+{
+  const ev = new Event('foo');
+  strictEqual(ev.cancelBubble, false);
+  ev.stopPropagation();
+  strictEqual(ev.cancelBubble, true);
+}
+{
+  const ev = new Event('foo');
+  strictEqual(ev.cancelBubble, false);
+  ev.cancelBubble = 'some-truthy-value';
+  strictEqual(ev.cancelBubble, true);
+}
 
 {
   const ev = new Event('foo', { cancelable: true });