Add reset method to EventBus in core

src/components/utils/EventBus.js

@@ -7,22 +7,33 @@ export default function() {
             eventKey = key;
             eventListener = function(e) { listener(e.detail); };
             eventTarget.addEventListener(type, eventListener);
+            return this;
         },
         once(type, listener, key) {
             eventTarget = eventTarget || document.body.appendChild(document.createComment(''));
             eventKey = key;
             eventListener = function(e) { listener(e.detail); };
             eventTarget.addEventListener(type, eventListener, { once: true });
+            return this;
         },
         off(type, key) {
             if (eventTarget && eventListener && eventKey === key) {
                 eventTarget.removeEventListener(type, eventListener);
             }
+            return this;
         },
         emit(type, detail) {
             if (eventTarget) {
                 eventTarget.dispatchEvent(new CustomEvent(type, { detail }));
             }
+            return this;
+        },
+        reset() {
+            if (eventTarget) {
+                document.body.removeChild(eventTarget);
+                eventTarget = eventListener = eventKey = undefined;
+            }
+            return this;
         }
     }
-}
+}

src/views/liveeditor/LiveEditor.vue

@@ -59,7 +59,7 @@ export default {
         });
     },
     beforeUnmount() {
-        EventBus.off('run-demo');
+        EventBus.off('run-demo').reset();
     },
     methods: {
         postSandboxParameters(sourceType) {