SPA Router

Check the console for the router's dev-mode configuration errors, look for earlier routes shadowing the missing one (a ** or :param too high), check pathMatch on parents and redirects, and trace navigations with withDebugTracing() to see which route matched or why matching failed.

Pass withNavigationErrorHandler(fn) to provideRouter; fn receives each NavigationError and runs in an injection context. Returning a RedirectCommand turns the error into a redirect; anything else is ignored, and it cannot stop navigate() from rejecting.

Angular invokes every guard in one canActivate array together and uses array order only to rank verdicts, so adminGuard's request always starts. It also ignores results other than boolean, UrlTree or RedirectCommand, so an unmapped response object passes.

Some eagerly loaded file still imports ReportsPage statically, directly or through a barrel, so the bundler must keep it in the initial chunk. Confirm with the build's initial and lazy chunk lists and a stats.json analysis.

Implement PreloadingStrategy in a root-provided class whose preload() calls load() only when the route is flagged for admins and the injected auth state says the user is one, returning of(null) otherwise. It is a performance hint, never access control.

Relative commands resolve against an ActivatedRoute. routerLink uses the one injected where it sits, which is the root route outside any router-outlet, and Router.navigate() uses the root unless relativeTo is passed, so both land at /edit.

A relative link resolves against the ActivatedRoute of the component it sits in, and Compose's route is the side outlet's branch, so '../sent' rewrites that branch to (side:sent). Use '/sent' or an outlets command naming primary.

The router reuses the component and, under the default runGuardsAndResolvers of 'paramsChange', ignores query parameters, so the resolver is skipped and the old data kept. Set a query-aware policy and read ActivatedRoute.data reactively.

Use a ResolveFn when the page is meaningless without the data or must redirect before rendering; fetch in the component when a skeleton is acceptable; route resources (developer preview in 22.2) add concurrency, optional non-blocking loads and reload without renavigating.

The router reuses the UserProfile instance for /users/2 because it matches the same route config, so ngOnInit and its snapshot read never run again. Derive the load from paramMap or a bound input, cancel superseded loads, and reset per-user state.

Extend TitleStrategy, override updateTitle(snapshot), call buildTitle(snapshot) for the deepest primary route's title, and set it with the Title service plus a suffix. Provide it with {provide: TitleStrategy, useClass: AppTitleStrategy}.

Use Route.matcher when path syntax cannot express the pattern, such as /@username or a regex rule. The function receives the URL segments and returns null for no match or {consumed, posParams}, whose parameters appear in paramMap like :id values.

Router.currentNavigation() returns the in-flight Navigation, or null when idle: its id, initialUrl, extractedUrl, finalUrl (set once routes are recognised), trigger, extras such as state, and previousNavigation. Calling its abort() cancels the navigation with the Aborted code, if activation has not started.

A RedirectCommand (v18+) wraps the target UrlTree with NavigationBehaviorOptions that override what the redirect would otherwise inherit from the original navigation, so a guard can set skipLocationChange, replaceUrl, state, info or browserUrl for the redirect.

activate emits the routed component instance when the outlet creates it, and deactivate emits it when the outlet destroys it. To send context into routed components, bind routerOutletData and inject ROUTER_OUTLET_DATA as a signal instead of poking the instance.

Since v22, paramsInheritanceStrategy defaults to 'always', so every route inherits its ancestors' params, static data and resolved data, and its own values win on a clash. The old default 'emptyOnly' inherited only for empty-path routes or componentless parents.