feat(overlays): delegate events in DynamicOverlayController

packages/overlays/src/DynamicOverlayController.js

@@ -34,6 +34,8 @@ export class DynamicOverlayController {
     if (!this.content) {
       this.content = document.createElement('div');
     }
+    this.__fakeExtendsEventTarget();
+    this.__delegateEvent = this.__delegateEvent.bind(this);
   }
 
   add(ctrlToAdd) {
@@ -71,9 +73,13 @@ export class DynamicOverlayController {
     if (this.isShown === true) {
       throw new Error('You can not switch overlays while being shown');
     }
+    const prevActive = this.active;
+
     this.active.switchOut();
     ctrlToSwitchTo.switchIn();
     this.__active = ctrlToSwitchTo;
+
+    this._delegateEvents(this.__active, prevActive);
   }
 
   async show() {
@@ -99,4 +105,24 @@ export class DynamicOverlayController {
   get invokerNode() {
     return this.active.invokerNode;
   }
+
+  _delegateEvents(active, prevActive) {
+    ['show', 'hide'].forEach(event => {
+      active.addEventListener(event, this.__delegateEvent);
+      prevActive.removeEventListener(event, this.__delegateEvent);
+    });
+  }
+
+  __delegateEvent(ev) {
+    ev.stopPropagation();
+    this.dispatchEvent(new Event(ev.type));
+  }
+
+  // TODO: this method has to be removed when EventTarget polyfill is available on IE11
+  __fakeExtendsEventTarget() {
+    const delegate = document.createDocumentFragment();
+    ['addEventListener', 'dispatchEvent', 'removeEventListener'].forEach(funcName => {
+      this[funcName] = (...args) => delegate[funcName](...args);
+    });
+  }
 }

packages/overlays/test/DynamicOverlayController.test.js

@@ -133,4 +133,34 @@ describe('DynamicOverlayController', () => {
     expect(globalOutSpy).to.have.callCount(1);
     expect(localInSpy).to.have.callCount(1);
   });
+
+  describe('API abstraction for active overlay controller', () => {
+    describe('Events', () => {
+      it('delegates "show/hide" event', async () => {
+        const ctrl = new DynamicOverlayController();
+        const global = new FakeGlobalCtrl(defaultOptions);
+        const local = new FakeLocalCtrl(defaultOptions);
+        ctrl.add(global);
+        ctrl.add(local);
+        ctrl.switchTo(local);
+
+        const showSpy = sinon.spy();
+        const hideSpy = sinon.spy();
+
+        ctrl.addEventListener('show', showSpy);
+        ctrl.addEventListener('hide', hideSpy);
+
+        await ctrl.show();
+        expect(showSpy.callCount).to.equal(1);
+        await ctrl.hide();
+        expect(hideSpy.callCount).to.equal(1);
+
+        ctrl.switchTo(global);
+        await ctrl.show();
+        expect(showSpy.callCount).to.equal(2);
+        await ctrl.hide();
+        expect(hideSpy.callCount).to.equal(2);
+      });
+    });
+  });
 });