• Using the Y formatter (week-numbering year) without also including w (week number) is now detected as suspicious date pattern, as y is typically intended.

• void in an expression now refers to the operator

  Previously an expression in the template like {{void}} referred to a property on the component class. After this change it now refers to the void operator, which would make the above example invalid. If you have existing expressions that need to refer to a property named void, change the expression to use this.void instead: {{this.void}}.

Blog post: https://blog.angular.dev/meet-angular-v19-7b29dfd05b84

• this.foo property reads no longer refer to template context variables. If you intended to read the template variable, do not use this..
• changes to CSS selectors parsing where introduced, mainly to: pseudo selectors :where() and :is(), parsing of :host and host-context, parsing selectors within pseudo selector arguments (for instance comma separated selectors). These changes could lead to a different specificity of the resulting selectors and/or previously broken selectors being applied now, for example :where(:host) used to transform to :where()[ng-host] and is being :where([ng-host]) now. Unlike the previous outcome, the new result can target elements and therefore could lead to breakages.

• Angular directives, components and pipes are now standalone by default.

  • Specify standalone: false for declarations that are currently declared in @NgModules.
  • ng update for v19 will take care of this automatically.

• TypeScript versions less than 5.5 are no longer supported.

• Timing changes for effect API (in developer preview):

  • effects which are triggered outside of change detection run as part of the change detection process instead of as a microtask. Depending on the specifics of application/test setup, this can result in them executing earlier or later (or requiring additional test steps to trigger; see below examples).

  • effects which are triggered during change detection (e.g. by input signals) run earlier, before the component's template.

• ExperimentalPendingTasks has been renamed to PendingTasks.

• The autoDetect feature of ComponentFixture will now attach the fixture to the ApplicationRef. As a result, errors during automatic change detection of the fixture be reported to the ErrorHandler. This change may cause custom error handlers to observe new failures that were previously unreported.

• createComponent will now render default fallback with empty projectableNodes.

  • When passing an empty array to projectableNodes in the createComponent API, the default fallback content of the ng-content will be rendered if present. To prevent rendering the default content, pass document.createTextNode('') as a projectableNode.

  // The first ng-content will render the default fallback content if present
  createComponent(MyComponent. { projectableNodes: [[], [secondNode]] });
  
  // To prevent projecting the default fallback content:
  createComponent(MyComponent. { projectableNodes: [[document.createTextNode('')], [secondNode]] });

• Errors that are thrown during ApplicationRef.tick will now be rethrown when using TestBed. These errors should be resolved by ensuring the test environment is set up correctly to complete change detection successfully. There are two alternatives to catch the errors:

  • Instead of waiting for automatic change detection to happen, trigger it synchronously and expect the error. For example, a jasmine test could write expect(() => TestBed.inject(ApplicationRef).tick()).toThrow()
  • TestBed will reject any outstanding ComponentFixture.whenStable promises. A jasmine test, for example, could write expectAsync(fixture.whenStable()).toBeRejected().

  As a last resort, you can configure errors to not be rethrown by setting rethrowApplicationErrors to false in TestBed.configureTestingModule.

• The timers that are used for zone coalescing and hybrid mode scheduling (which schedules an application state synchronization when changes happen outside the Angular zone) will now run in the zone above Angular rather than the root zone. This will mostly affect tests which use fakeAsync: these timers will now be visible to fakeAsync and can be affected by tick or flush.

• The deprecated factories property in KeyValueDiffers has been removed.

• as part of switching away from custom CD behavior to the hybrid scheduler, timing of change detection around custom elements has changed subtly. These changes make elements more efficient, but can cause tests which encoded assumptions about how or when elements would be checked to require updating.

• The name option in the ng add @localize`` schematic has been removed in favor of the project option.

• The deprecated BrowserModule.withServerTransition method has been removed. Please use the APP_ID DI token to set the application id instead.

• The Router.errorHandler property has been removed. Adding an error handler should be configured in either withNavigationErrorHandler with provideRouter or the errorHandler property in the extra options of RouterModule.forRoot. In addition, the error handler cannot be used to change the return value of the router navigation promise or prevent it from rejecting. Instead, if you want to prevent the promise from rejecting, use resolveNavigationPromiseOnError.
• The return type of the Resolve interface now includes RedirectCommand.

Blog post "Angular v18 is now available".

• Deprecated matchesElement method has been removed from AnimationDriver as it is unused.

• The deprecated isPlatformWorkerUi and isPlatformWorkerApp have been removed without replacement, as they serve no purpose since the removal of the WebWorker platform.

• Angular only supports writable expressions inside of two-way bindings.

• • Angular no longer supports TypeScript versions older than 5.4.

• OnPush views at the root of the application need to be marked dirty for their host bindings to refresh. Previously, the host bindings were refreshed for all root views without respecting the OnPush change detection strategy.

• The ComponentFixture autoDetect feature will no longer refresh the component's host view when the component is OnPush and not marked dirty. This exposes existing issues in components which claim to be OnPush but do not correctly call markForCheck when they need to be refreshed. If this change causes test failures, the easiest fix is to change the component to ChangeDetectionStrategy.Default.

• ComponentFixture.whenStable now matches the ApplicationRef.isStable observable. Prior to this change, stability of the fixture did not include everything that was considered in ApplicationRef. whenStable of the fixture will now include unfinished router navigations and unfinished HttpClient requests. This will cause tests that await the whenStable promise to time out when there are incomplete requests. To fix this, remove the whenStable, instead wait for another condition, or ensure HttpTestingController mocks responses for all requests. Try adding HttpTestingController.verify() before your await fixture.whenStable to identify the open requests. Also, make sure your tests wait for the stability promise. We found many examples of tests that did not, meaning the expectations did not execute within the test body.

  In addition, ComponentFixture.isStable would synchronously switch to true in some scenarios but will now always be asynchronous.

• Angular will ensure change detection runs, even when the state update originates from outside the zone, tests may observe additional rounds of change detection compared to the previous behavior.

  This change will be more likely to impact existing unit tests. This should usually be seen as more correct and the test should be updated, but in cases where it is too much effort to debug, the test can revert to the old behavior by adding provideZoneChangeDetection({schedulingMode: NgZoneSchedulingMode.NgZoneOnly}) to the TestBed providers.

  Similarly, applications which may want to update state outside the zone and not trigger change detection can add provideZoneChangeDetection({schedulingMode: NgZoneSchedulingMode.NgZoneOnly}) to the providers in bootstrapApplication or add schedulingMode: NgZoneSchedulingMode.NgZoneOnly to the BootstrapOptions of bootstrapModule.

• When Angular runs change detection, it will continue to refresh any views attached to ApplicationRef that are still marked for check after one round completes. In rare cases, this can result in infinite loops when certain patterns continue to mark views for check using ChangeDetectorRef.detectChanges. This will be surfaced as a runtime error with the NG0103 code.

• async has been removed, use waitForAsync instead.

• The ComponentFixture.autoDetect feature now executes change detection for the fixture within ApplicationRef.tick. This more closely matches the behavior of how a component would refresh in production. The order of component refresh in tests may be slightly affected as a result, especially when dealing with additional components attached to the application, such as dialogs. Tests sensitive to this type of change (such as screenshot tests) may need to be updated. Concretely, this change means that the component will refresh before additional views attached to ApplicationRef (i.e. dialog components). Prior to this change, the fixture component would refresh after other views attached to the application.

• The exact timing of change detection execution when using event or run coalescing with NgZone is now the first of either setTimeout or requestAnimationFrame. Code which relies on this timing (usually by accident) will need to be adjusted. If a callback needs to execute after change detection, we recommend afterNextRender instead of something like setTimeout.

• Newly created and views marked for check and reattached during change detection are now guaranteed to be refreshed in that same change detection cycle. Previously, if they were attached at a location in the view tree that was already checked, they would either throw ExpressionChangedAfterItHasBeenCheckedError or not be refreshed until some future round of change detection. In rare circumstances, this correction can cause issues. We identified one instance that relied on the previous behavior by reading a value on initialization which was queued to be updated in a microtask instead of being available in the current change detection round. The component only read this value during initialization and did not read it again after the microtask updated it.

• Testability methods increasePendingRequestCount, decreasePendingRequestCount and getPendingRequestCount have been removed. This information is tracked with zones.

• By default we now prevent caching of HTTP requests that require authorization . To opt-out from this behaviour use the includeRequestsWithAuthHeaders option in withHttpTransferCache.

  Example:

  withHttpTransferCache({
    includeRequestsWithAuthHeaders: true,
  })

• Deprecated StateKey, TransferState and makeStateKey have been removed from @angular/platform-browser, use the same APIs from @angular/core.

• No longer used RESOURCE_CACHE_PROVIDER APIs have been removed.

• deprecated platformDynamicServer has been removed. Add an import @angular/compiler and replace the usage with platformServer

• deprecated ServerTransferStateModule has been removed. TransferState can be use without providing this module.

• deprecated useAbsoluteUrl and baseUrl been removed from PlatformConfig. Provide and absolute url instead.

• Legacy handling or Node.js URL parsing has been removed from ServerPlatformLocation.

  The main differences are;

  • pathname is always suffixed with a /.
  • port is empty when http: protocol and port in url is 80
  • port is empty when https: protocol and port in url is 443

• Guards can now return RedirectCommand for redirects in addition to UrlTree. Code which expects only boolean or UrlTree values in Route types will need to be adjusted.
• This change allows Route.redirectTo to be a function in addition to the previous string. Code which expects redirectTo to only be a string on Route objects will need to be adjusted.
• When a a guard returns a UrlTree as a redirect, the redirecting navigation will now use replaceUrl if the initial navigation was also using the replaceUrl option. If this is not desirable, the redirect can configure new NavigationBehaviorOptions by returning a RedirectCommand with the desired options instead of UrlTree.
• Providers available to the routed components always come from the injector heirarchy of the routes and never inherit from the RouterOutlet. This means that providers available only to the component that defines the RouterOutlet will no longer be available to route components in any circumstances. This was already the case whenever routes defined providers, either through lazy loading an NgModule or through explicit providers on the route config.
• Providers available to the routed components always come from the injector heirarchy of the routes and never inherit from the RouterOutlet. This means that providers available only to the component that defines the RouterOutlet will no longer be available to route components in any circumstances. This was already the case whenever routes defined providers, either through lazy loading an NgModule or through explicit providers on the route config.

• getCurrencySymbol, getLocaleCurrencyCode, getLocaleCurrencyName, getLocaleCurrencySymbol, getLocaleDateFormat, getLocaleDateTimeFormat, getLocaleDayNames, getLocaleDayPeriods, getLocaleDirection, getLocaleEraNames, getLocaleExtraDayPeriodRules, getLocaleExtraDayPeriods, getLocaleFirstDayOfWeek, getLocaleId, getLocaleMonthNames, getLocaleNumberFormat, getLocaleNumberSymbol, getLocalePluralCase, getLocaleTimeFormat, getLocaleWeekEndRange, getNumberOfCurrencyDigits

• @Component.interpolation is deprecated. Use Angular's delimiters instead.

• HttpClientModule, HttpClientXsrfModule and HttpClientJsonpModule

  As mentionned, those modules can be replaced by provider function only.