fix(router): Scroll restoration should use instant scroll behavior for traversals

atscott · atscott · commit 78b4d853957f · 2025-10-06T16:55:51.000-07:00
When the scroll position is being restored, this change upates the behavior to use 'instant' rather than the default 'auto', which will be whatever the browser behavior is for 'window.scrollTo'. The 'smooth' behavior does not match how browsers behavior when performing a traversal navigation for MPAs, which is 'instant'. related to #58258
diff --git a/packages/router/src/router_scroller.ts b/packages/router/src/router_scroller.ts
@@ -85,12 +85,13 @@ export class RouterScroller implements OnDestroy {
   private consumeScrollEvents() {
     return this.transitions.events.subscribe((e) => {
       if (!(e instanceof Scroll)) return;
+      const instantScroll: ScrollOptions = {behavior: 'instant'};
       // a popstate event. The pop state event will always ignore anchor scrolling.
       if (e.position) {
         if (this.options.scrollPositionRestoration === 'top') {
-          this.viewportScroller.scrollToPosition([0, 0]);
+          this.viewportScroller.scrollToPosition([0, 0], instantScroll);
         } else if (this.options.scrollPositionRestoration === 'enabled') {
-          this.viewportScroller.scrollToPosition(e.position);
+          this.viewportScroller.scrollToPosition(e.position, instantScroll);
         }
         // imperative navigation "forward"
       } else {
