angular 2 ngIf and CSS transition/animation

Question

I want a div to slide in from the right in angular 2 using css.

Answer 1

One way is to use a setter for the ngIf property and set the state as part of updating the value.

StackBlitz example

fade.component.ts

 import {
    animate,
    AnimationEvent,
    state,
    style,
    transition,
    trigger
  } from '@angular/animations';
  import { ChangeDetectionStrategy, Component, Input } from '@angular/core';

  export type FadeState = 'visible' | 'hidden';

  @Component({
    selector: 'app-fade',
    templateUrl: './fade.component.html',
    styleUrls: ['./fade.component.scss'],
    animations: [
      trigger('state', [
        state(
          'visible',
          style({
            opacity: '1'
          })
        ),
        state(
          'hidden',
          style({
            opacity: '0'
          })
        ),
        transition('* => visible', [animate('500ms ease-out')]),
        transition('visible => hidden', [animate('500ms ease-out')])
      ])
    ],
    changeDetection: ChangeDetectionStrategy.OnPush
  })
  export class FadeComponent {
    state: FadeState;
    // tslint:disable-next-line: variable-name
    private _show: boolean;
    get show() {
      return this._show;
    }
    @Input()
    set show(value: boolean) {
      if (value) {
        this._show = value;
        this.state = 'visible';
      } else {
        this.state = 'hidden';
      }
    }

    animationDone(event: AnimationEvent) {
      if (event.fromState === 'visible' && event.toState === 'hidden') {
        this._show = false;
      }
    }
  }

fade.component.html

 

    test
  

example.component.css

:host {
  display: block;
}
.fade {
  opacity: 0;
}