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How to set the initial index (position) for the CdkVirtualScrollViewport in Angular 7

I need the inital position of the cdk-virtual-scroll-viewport to be other than the first element / item of the list.

Now I found the scrollToIndex and scrollTo methods, but I only can get them to work when using it in the ngAfterViewChecked, which feels off.

  1. Can someone confirm that the using those methods in the ngAfterViewChecked is the right way of doing things?
  2. If not, show an alternative method / technique?

  @ViewChild(CdkVirtualScrollViewport) cdkVirtualScrollViewport: CdkVirtualScrollViewport;
  numbers: number[] = [];

  constructor() {
    for (let index = 0; index < 10000; index++) {
      this.numbers.push(index);
    }
  }

  ngAfterViewChecked() {
    this.cdkVirtualScrollViewport.scrollToIndex(2000);
  }
  <ul class="list">
    <cdk-virtual-scroll-viewport style="height:264px" itemSize="88">
      <ng-container *cdkVirtualFor="let n of numbers">
        <li style="height:88px">{{ n }}</li>
      </ng-container>
    </cdk-virtual-scroll-viewport>
  </ul>
like image 613
Dalie Avatar asked Nov 12 '18 19:11

Dalie


1 Answers

I have the same problem, I have a not so elegant solution

contentCheck = 0

ngAfterViewChecked() {
  if (this.contentCheck < 3) {
  this. cdkVirtualScrollViewport.scrollToIndex(4000);
  this.contentCheck++;
 }
}

After 3 checks the scrollToIndex works.

like image 106
Pablo Cid Avatar answered Oct 24 '22 11:10

Pablo Cid