Staggering Angular2 animations within *ngFor

Question

I\'ve been digging around the Angular2 documentation and there doesn\'t seem to be a simple way to add delays to animations. For reference, here is what I\'m aiming to achie

Answer 1

Since Angular 4.2.6 you can use query(), stagger() and animateChild() to stagger all kinds of animations. Here's an example:

template: `
    <div [@stagger]>
      <div [@fade] *ngFor="let item of items;">{{item}}</div>
    </div>
  `,
animations: [
    trigger('fade', [
      transition(':enter', [style({opacity: 0}), animate('.6s ease')])
    ]),
    trigger('stagger', [
      transition(':enter', [
        query(':enter', stagger('.3s', [animateChild()]))
      ])
    ])
  ]

Plunker: https://embed.plnkr.co/pQQSZETi7mnToB6lqfID/

Answer 2

After hammering my head against the animation DSL to make staggering animations a thing. I found an alternative way of doing animations which allows staggering!

The trick is to have a directive responsible of the animation using the Renderer and Service to hold your animation store!

Directive important code

this.animation = this.renderer.animate(
  this.element.nativeElement.firstElementChild || this.element.nativeElement,
  this.animService.getAnimation(animationName).startingStyles,
  this.animService.getAnimation(animationName).keyframes,
  this.duration,
  this.delay,
  this.easing
);
this.animation.pause();
this.animation.play();

How to use it in template

<div *ngFor="let str of ['foo','bar','baz']; let i = index"
  anim-aes
  [anim-aes-delay]="i*200"
  [anim-aes-duration]="500"
  [anim-aes-animation]="'fadeIn'"
  [anim-aes-animation-leave]="'fadeOut'"
  [anim-aes-play]="show">
  click {{str}}
</div>

I made a working plunkr with everything you need!

plunkr

Answer 3

The staggering module is still not ready. But there are some hacky paths to archieve the same effect.

1. If you have a fixed list in size (or at least at screen). You can write a stagger function that returns a delayed animation for every state throught 0 to n. the stagger function should return AnimationEntryMetadata[] Then. you should pass bind the @expandSkill to the variable i on the loop. On the end, you will be creating dynamic, in animations for every object.

2. Another option you have, is use, the Renderer plus a ViewChildren, query the childs, and create the stagger animation with css styles. The renderer provides a setElementStyle.

3. There is a thirth option, a little more hacky.. Render a new list, an populate it throught a setTimeout.

I used the two for some rich animations. Sure there are better aproaches :)