How can I create simple accordion with Angular 2?

try this solution, this is very simple accordion:

app/accordion.component.ts

import { Component, Input, Output, EventEmitter } from '@angular/core';

@Component({
  selector: 'tp-accordion',
  template: `
    <h2 class="accordion-head" (click)="onClick($event)">{{ title }}</h2>
    <div class="accordion-body" [class.active]="active">
      <ng-content></ng-content>
    </div>
  `,
  styles: [
    `
    .accordion-head {
      cursor: pointer;
    }
    .accordion-body {
      display: none;
    }
    .accordion-body.active {
      display: block;
      -webkit-animation: fadeIn .3s;
      animation: fadeIn .3s;
    }
    @-webkit-keyframes fadeIn {
      from { opacity: 0; transform: scale(0); }
        to { opacity: 1; transform: scale(1); }
    }  
    @keyframes fadeIn {
      from { opacity: 0; transform: scale(0); }
        to { opacity: 1; transform: scale(1); }
    }
    `  
  ],
})
export class Accordion {

  @Input() title: string;

  @Input() active: boolean = false;

  @Output() toggleAccordion: EventEmitter<boolean> = new EventEmitter();

  constructor() {}

  onClick(event) {
    event.preventDefault();
    this.toggleAccordion.emit(this.active);
  }

}

app/accordion-group.component.ts

import { Component, ContentChildren, QueryList, AfterContentInit, OnDestroy } from '@angular/core';

import { Accordion } from './accordion.component';

@Component({
  selector: 'tp-accordion-group',
  template: `
    <ng-content></ng-content>
  `
})
export class AccordionGroup {

  @ContentChildren(Accordion) accordions: QueryList<Accordion>;
  private subscriptions = [];

  private _accordions = [];

  constructor() {}

  ngAfterContentInit() {

    this._accordions = this.accordions;
    this.removeSubscriptions();
    this.addSubscriptions();

    this.accordions.changes.subscribe(rex => {
      this._accordions = rex;
      this.removeSubscriptions();
      this.addSubscriptions();
    });
  }

  addSubscriptions() {
    this._accordions.forEach(a => {
      let subscription = a.toggleAccordion.subscribe(e => {
        this.toogleAccordion(a);
      });
      this.subscriptions.push(subscription);
    });
  }

  removeSubscriptions() {
    this.subscriptions.forEach(sub => {
      sub.unsubscribe();
    });
  }

  toogleAccordion(accordion) {
    if (!accordion.active) {
      this.accordions.forEach(a => a.active = false);
    }
    // set active accordion
    accordion.active = !accordion.active;
  }

  ngOnDestroy() {
    this.removeSubscriptions();
  }

}

app/app.component.ts

import { Component, OnInit, OnDestroy } from '@angular/core';
import { PostsService } from './posts.service';


@Component({
  selector: 'app-root',
  template: `
    <tp-accordion-group>
      <tp-accordion *ngFor="let post of posts" [title]="post.title">
        {{ post.body }}
      </tp-accordion>
    </tp-accordion-group>
  `
})
export class AppComponent implements OnInit, OnDestroy {

  posts = [];
  private subscription: any;

  constructor(private postsSvc: PostsService) {}

  ngOnInit() {
    this.subscription = this.postsSvc.getPosts().subscribe(res => {
      if (res.length) {
        this.posts = res.slice(0, 10);
      }
    })
  }

  ngOnDestroy() {
    if (this.subscription) {
      this.subscription.unsubscribe();
    }
  }

}

app/posts.service.ts

import { Injectable } from '@angular/core';
import { Http } from '@angular/http';
import 'rxjs/add/operator/map';
import 'rxjs/add/operator/catch';

@Injectable()
export class PostsService {
  postsUrl: 'https://jsonplaceholder.typicode.com/posts';
  constructor(private http: Http) {

  }
  getPosts() {
    return this.http.get(this.postsUrl)
      .map(res => {
        let body = res.json();
        return body || [];
      })
      .catch(console.log);
  }
}

Online demo: https://plnkr.co/edit/xFBllK?p=preview

Document:

• EventEmitter
• @ContentChildren
• QueryList