--- a/dom/animation/AnimationEffectTiming.cpp
+++ b/dom/animation/AnimationEffectTiming.cpp
@@ -93,17 +93,23 @@ AnimationEffectTiming::SetDuration(const
   mTiming.mDuration = newDuration;
 
   PostSpecifiedTimingUpdated(mEffect);
 }
 
 void
 AnimationEffectTiming::SetDirection(const PlaybackDirection& aDirection)
 {
-  // TODO: Bug 1244642 - implement AnimationEffectTiming direction
+  if (mTiming.mDirection == aDirection) {
+    return;
+  }
+
+  mTiming.mDirection = aDirection;
+
+  PostSpecifiedTimingUpdated(mEffect);
 }
 
 void
 AnimationEffectTiming::SetEasing(const nsAString& aEasing, ErrorResult& aRv)
 {
   // TODO: Bug 1244643 - implement AnimationEffectTiming easing
 }