Route transition animations in Angular

src/app/app.module.ts

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { BrowserAnimationsModule } from '@angular/platform-browser/animations';
import { RouterModule } from '@angular/router';
import { AppComponent } from './app.component';
import { OpenCloseComponent } from './open-close.component';
import { OpenClosePageComponent } from './open-close-page.component';
import { OpenCloseChildComponent } from './open-close.component.4';
import { ToggleAnimationsPageComponent } from './toggle-animations-page.component';
import { StatusSliderComponent } from './status-slider.component';
import { StatusSliderPageComponent } from './status-slider-page.component';
import { HeroListPageComponent } from './hero-list-page.component';
import { HeroListGroupPageComponent } from './hero-list-group-page.component';
import { HeroListGroupsComponent } from './hero-list-groups.component';
import { HeroListEnterLeavePageComponent } from './hero-list-enter-leave-page.component';
import { HeroListEnterLeaveComponent } from './hero-list-enter-leave.component';
import { HeroListAutoCalcPageComponent } from './hero-list-auto-page.component';
import { HeroListAutoComponent } from './hero-list-auto.component';
import { HomeComponent } from './home.component';
import { AboutComponent } from './about.component';
import { InsertRemoveComponent } from './insert-remove.component';


@NgModule({
  imports: [
    BrowserModule,
    BrowserAnimationsModule,
    RouterModule.forRoot([
      { path: '', pathMatch: 'full', redirectTo: '/enter-leave' },
      { path: 'open-close', component: OpenClosePageComponent },
      { path: 'status', component: StatusSliderPageComponent },
      { path: 'toggle', component: ToggleAnimationsPageComponent },
      { path: 'heroes', component: HeroListPageComponent, data: {animation: 'FilterPage'} },
      { path: 'hero-groups', component: HeroListGroupPageComponent },
      { path: 'enter-leave', component: HeroListEnterLeavePageComponent },
      { path: 'auto', component: HeroListAutoCalcPageComponent },
      { path: 'home', component: HomeComponent, data: {animation: 'HomePage'} },
      { path: 'about', component: AboutComponent, data: {animation: 'AboutPage'} },

    ])
  ],

src/app/app.component.html

<div [@routeAnimations]="prepareRoute(outlet)" >
  <router-outlet #outlet="outlet"></router-outlet>
</div>

src/app/app.component.ts

prepareRoute(outlet: RouterOutlet) {
  return outlet && outlet.activatedRouteData && outlet.activatedRouteData['animation'];
}

src/app/animations.ts

export const slideInAnimation =
  trigger('routeAnimations', [
    transition('HomePage <=> AboutPage', [
      style({ position: 'relative' }),
      query(':enter, :leave', [
        style({
          position: 'absolute',
          top: 0,
          left: 0,
          width: '100%'
        })
      ]),
      query(':enter', [
        style({ left: '-100%'})
      ]),
      query(':leave', animateChild()),
      group([
        query(':leave', [
          animate('300ms ease-out', style({ left: '100%'}))
        ]),
        query(':enter', [
          animate('300ms ease-out', style({ left: '0%'}))
        ])
      ]),
      query(':enter', animateChild()),
    ]),
    transition('* <=> FilterPage', [
      style({ position: 'relative' }),
      query(':enter, :leave', [
        style({
          position: 'absolute',
          top: 0,
          left: 0,
          width: '100%'
        })
      ]),
      query(':enter', [
        style({ left: '-100%'})
      ]),
      query(':leave', animateChild()),
      group([
        query(':leave', [
          animate('200ms ease-out', style({ left: '100%'}))
        ]),
        query(':enter', [
          animate('300ms ease-out', style({ left: '0%'}))
        ])
      ]),
      query(':enter', animateChild()),
    ])
  ]);

src/app/app.component.ts

@Component({
  selector: 'app-root',
  templateUrl: 'app.component.html',
  styleUrls: ['app.component.css'],
  animations: [
    slideInAnimation
    // animation triggers go here
  ]
})

fade animation

export const fadeAnimation2 =
  trigger('routeAnimations', [
    transition('* <=> *', [
      style({
        opacity: 0
      }),
      query(':enter, :leave', [
        style({
          opacity: 0
        }),
      ], {optional: true}),
      // Animate the new page in
      query(':enter', [
        animate('200ms ease-in', style({
          opacity: 1
        })),
      ], {optional: true})
    ]),
  ]);

References
https://angular.io/guide/route-animations
https://fireship.io/lessons/angular-router-animations/