Workaround for M$ Edge resetting defaultPrevented flag upon dispatchEvent

2 files changed, 41 insertions, 1 deletions

diff --git a/js/src/dom/eventHandler.js b/js/src/dom/eventHandler.js
index a69ab6136..b72684f81 100644
--- a/js/src/dom/eventHandler.js
+++ b/js/src/dom/eventHandler.js
@@ -16,6 +16,8 @@ const workingDefaultPrevented = (() => {
   return e.defaultPrevented
 })()
 
+let defaultPreventedPreservedOnDispatch = true
+
 // CustomEvent polyfill for IE (see: https://mzl.la/2v76Zvn)
 if (typeof window.CustomEvent !== 'function') {
   window.CustomEvent = (event, params) => {
@@ -46,6 +48,20 @@ if (typeof window.CustomEvent !== 'function') {
   }
 
   window.CustomEvent.prototype = window.Event.prototype
+} else {
+  // MSEdge resets defaultPrevented flag upon dispatchEvent call if at least one listener is attached
+  defaultPreventedPreservedOnDispatch = (() => {
+    const e = new CustomEvent('Bootstrap', {
+      cancelable: true
+    })
+
+    const element = document.createElement('div')
+    element.addEventListener('Bootstrap', () => null)
+
+    e.preventDefault()
+    element.dispatchEvent(e)
+    return e.defaultPrevented
+  })()
 }
 
 // Event constructor shim
@@ -276,7 +292,7 @@ const EventHandler = {
 
     if (isNative) {
       evt = document.createEvent('HTMLEvents')
-      evt.initEvent(typeEvent, true, true)
+      evt.initEvent(typeEvent, bubbles, true)
     } else {
       evt = new CustomEvent(event, {
         bubbles,
@@ -291,6 +307,12 @@ const EventHandler = {
 
     if (defaultPrevented) {
       evt.preventDefault()
+
+      if (!defaultPreventedPreservedOnDispatch) {
+        Object.defineProperty(evt, 'defaultPrevented', {
+          get: () => true
+        })
+      }
     }
 
     if (nativeDispatch) {
diff --git a/js/tests/unit/dom/eventHandler.js b/js/tests/unit/dom/eventHandler.js
index 49cc89c65..0730e3846 100644
--- a/js/tests/unit/dom/eventHandler.js
+++ b/js/tests/unit/dom/eventHandler.js
@@ -59,6 +59,24 @@ $(function () {
     EventHandler.trigger(element, 'foobar.namespace')
   })
 
+  QUnit.test('should mirror preventDefault for native events', function (assert) {
+    assert.expect(2)
+
+    var element = document.createElement('div')
+    document.body.appendChild(element)
+
+    $(element).on('click', function (event) {
+      event.preventDefault()
+      assert.ok(true, 'first listener called')
+    })
+    element.addEventListener('click', function (event) {
+      assert.ok(event.defaultPrevented, 'defaultPrevented is true in second listener')
+    })
+
+    EventHandler.trigger(element, 'click')
+    document.body.removeChild(element)
+  })
+
   QUnit.test('on should add event listener', function (assert) {
     assert.expect(1)