fix(animations): avoid animation insertions during router back/refresh (#21977)

matsko · Matias Niemelä · commit 641cc493ffbf · 2018-03-22T17:59:41.000-04:00
Closes #19712 PR Close #21977
diff --git a/packages/animations/browser/src/render/transition_animation_engine.ts b/packages/animations/browser/src/render/transition_animation_engine.ts
@@ -665,7 +665,16 @@ export class TransitionAnimationEngine {
     // code does not contain any animation code in it, but it is
     // just being called so that the node is marked as being inserted
     if (namespaceId) {
-      this._fetchNamespace(namespaceId).insertNode(element, parent);
+      const ns = this._fetchNamespace(namespaceId);
+      // This if-statement is a workaround for router issue #21947.
+      // The router sometimes hits a race condition where while a route
+      // is being instantiated a new navigation arrives, triggering leave
+      // animation of DOM that has not been fully initialized, until this
+      // is resolved, we need to handle the scenario when DOM is not in a
+      // consistent state during the animation.
+      if (ns) {
+        ns.insertNode(element, parent);
+      }
     }
 
     // only *directives and host elements are inserted before
