Add StopPropagation for events

dom.go

@@ -91,6 +91,9 @@ func (e *Element) Reconcile(oldComp Component) {
 			if l.callPreventDefault {
 				jsEvent.Call("preventDefault")
 			}
+			if l.callStopPropagation {
+				jsEvent.Call("stopPropagation")
+			}
 			l.Listener(&Event{Target: jsEvent.Get("target")})
 		}
 	}

markup.go

@@ -99,10 +99,11 @@ func Style(name string, value interface{}) Markup {
 // EventListener is markup that specifies a callback function to be invoked when
 // the named DOM event is fired.
 type EventListener struct {
-	Name               string
-	Listener           func(*Event)
-	callPreventDefault bool
-	wrapper            func(jsEvent *js.Object)
+	Name                string
+	Listener            func(*Event)
+	callPreventDefault  bool
+	callStopPropagation bool
+	wrapper             func(jsEvent *js.Object)
 }
 
 // PreventDefault prevents the default behavior of the event from occuring.
@@ -113,6 +114,15 @@ func (l *EventListener) PreventDefault() *EventListener {
 	return l
 }
 
+// StopPropagation prevents further propagation of the current event in the
+// capturing and bubbling phases.
+//
+// See https://developer.mozilla.org/en-US/docs/Web/API/Event/stopPropagation.
+func (l *EventListener) StopPropagation() *EventListener {
+	l.callStopPropagation = true
+	return l
+}
+
 // Apply implements the Markup interface.
 func (l *EventListener) Apply(element *Element) {
 	element.EventListeners = append(element.EventListeners, l)