Infinite scroll with appending elements angular2

Question

I would like to implement infinite scroll whose key feature is possibility to add new elements instead actualising whole content of list.

Currently I try with ng-infinite-scroll but as a result of using ngFor it every time renders whole list from the beginning.

<div style="width: 750px;">
<div class="posts-list" 
infinite-scroll 
[infiniteScrollDistance]="2" 
[infiniteScrollThrottle]="300" 
(scrolled)="onScrollDown()">
    <post-component *ngFor="let item of array" [dataHref]="item"></post-component>
</div>

Such approach causing that elements fetch their data (what leads to unacceptable delays). I thought if it would be achievable to realize such thing with child components in router module (but this sounds bad because I don't have finite list of posts).

Anyone has ideas how to add new elements without repeating those which were already rendered?

Kasper Due · Accepted Answer · 2017-09-19 21:51:40Z

One way to create infinite scrolling, is as following.

1 - Add scroll event to your target div. (to track scroll event, and create a post component when condition is met.) 2 - Add ng-template inside your div (to inject a template in DOM)

HTML

<div style="width: 750px;">
   <div class="posts-list"(scroll)="onScroll($event)">
      <ng-template #post></ng-template>
   </div>
</div>

In your ts file, add a function that will create a component dynamically based on a condition when you have scroll (eg. 80% of your target div)

TS

@ViewChild('post') element: ElementRef;

constructor(private viewContainerRef: ViewContainerRef, private componentFactoryResolver: ComponentFactoryResolver){}

onScroll($event): void {
  // apply condition eg. when 80 % of div is scrolled
  if(conditionIsMet){
    this.loadPostComponent();
  }
}

loadPostComponent() {
  let postComponent = this.componentFactoryResolver.resolveComponentFactory(PostComponent);
  let componentRef = this.element.createComponent(postComponent);
  (<PostComponent>componentRef.instance).data = post.data;
}

Hope that helps you.

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