diff --git a/dom/events/KeyboardEvent.cpp b/dom/events/KeyboardEvent.cpp
index 9301acd6766d..de9d640c58ad 100644
--- a/dom/events/KeyboardEvent.cpp
+++ b/dom/events/KeyboardEvent.cpp
@@ -136,6 +136,41 @@ KeyboardEvent::GetCode(nsAString& aCodeName)
   mEvent->AsKeyboardEvent()->GetDOMCodeName(aCodeName);
 }
 
+void KeyboardEvent::GetInitDict(KeyboardEventInit& aParam)
+{
+  GetKey(aParam.mKey);
+  GetCode(aParam.mCode);
+  aParam.mLocation = Location();
+  aParam.mRepeat = Repeat();
+  aParam.mIsComposing = IsComposing();
+
+  // legacy attributes
+  aParam.mKeyCode = KeyCode();
+  aParam.mCharCode = CharCode();
+  aParam.mWhich = Which();
+
+  // modifiers from EventModifierInit
+  aParam.mCtrlKey = CtrlKey();
+  aParam.mShiftKey = ShiftKey();
+  aParam.mAltKey = AltKey();
+  aParam.mMetaKey = MetaKey();
+
+  WidgetKeyboardEvent* internalEvent = mEvent->AsKeyboardEvent();
+  aParam.mModifierAltGraph = internalEvent->IsAltGraph();
+  aParam.mModifierCapsLock = internalEvent->IsCapsLocked();
+  aParam.mModifierFn = internalEvent->IsFn();
+  aParam.mModifierFnLock = internalEvent->IsFnLocked();
+  aParam.mModifierNumLock = internalEvent->IsNumLocked();
+  aParam.mModifierOS = internalEvent->IsOS();
+  aParam.mModifierScrollLock = internalEvent->IsScrollLocked();
+  aParam.mModifierSymbol = internalEvent->IsSymbol();
+  aParam.mModifierSymbolLock = internalEvent->IsSymbolLocked();
+
+  // EventInit
+  aParam.mBubbles =  internalEvent->mFlags.mBubbles;
+  aParam.mCancelable = internalEvent->mFlags.mCancelable;
+}
+
 NS_IMETHODIMP
 KeyboardEvent::GetCharCode(uint32_t* aCharCode)
 {
diff --git a/dom/events/KeyboardEvent.h b/dom/events/KeyboardEvent.h
index 95dfec1e2976..ee860c401475 100644
--- a/dom/events/KeyboardEvent.h
+++ b/dom/events/KeyboardEvent.h
@@ -60,6 +60,7 @@ public:
   uint32_t Location();
 
   void GetCode(nsAString& aCode);
+  void GetInitDict(KeyboardEventInit& aParam);
 
   void InitKeyEvent(const nsAString& aType, bool aCanBubble, bool aCancelable,
                     nsGlobalWindow* aView, bool aCtrlKey, bool aAltKey,
diff --git a/dom/webidl/KeyboardEvent.webidl b/dom/webidl/KeyboardEvent.webidl
index d63c82af82d5..f6b7b33c550e 100644
--- a/dom/webidl/KeyboardEvent.webidl
+++ b/dom/webidl/KeyboardEvent.webidl
@@ -29,6 +29,11 @@ interface KeyboardEvent : UIEvent
   readonly attribute DOMString key;
   [Pref="dom.keyboardevent.code.enabled"]
   readonly attribute DOMString code;
+
+  // This returns the initialized dictionary for generating a
+  // same-type keyboard event
+  [Cached, ChromeOnly, Constant]
+  readonly attribute KeyboardEventInit initDict;
 };
 
 dictionary KeyboardEventInit : EventModifierInit