Question: SOLVED: 
My bad.The problem is in my code logic, the tempLatest array is always empty so the array that contains the card never been updated. btw, thank you for all your answers

I want to create a program that show a collection of card. That collection will be updated every 15 seconds. But here comes the problem, the v-for doesn't update directly when a new card added to the list but when the page is refreshed it shows the proper output.

here is my code

```
<PersonCard v-for="item in latest" v-bind:key="item.id" :attendeeName="item.name" :image="item.picture" :department="item.department"/>

```

```
data() {
        return {
            latest: [],
            imgArr: [],
            notReady: true,
        }
    }

```

```
created() {
        console.log(this.site, this.sinceTime)
        this.fetchRecognizedFace();
        this.timer = setInterval(this.fetchRecognizedFace, 15000);
    }

```

```
// update this.latest
for (var j = 0; j < tempLatest.length; j++) {
    this.latest.unshift(tempLatest[j]);
}

```

Answer: 
This is quite easy. Just use copyArrayItem instead of transferArrayItem

```
import {
  CdkDragDrop,
  copyArrayItem,
  moveItemInArray
} from '@angular/cdk/drag-drop';

drop(event: CdkDragDrop<string[]>) {
    if (event.previousContainer === event.container) {
      moveItemInArray(
        event.container.data,
        event.previousIndex,
        event.currentIndex
      );
    } else {
      copyArrayItem(
        event.previousContainer.data,
        event.container.data,
        event.previousIndex,
        event.currentIndex
      );
    }
  }

```
If you don't want the item removed while copying, use the cdkDragStarted like this in your HTML:

```
(cdkDragStarted)="dragStarted($event, dataList, index)"

```

and the method:

```
dragStarted(event: CdkDragStart, dataList, index) {
 if (this.dropMode  === 'copy') {
   dataList.splice(index, 0, event.source.data);
 }
}

onDropped(event) {
  event.previousContainer.dataList.splice(event.previousIndex,1);

  // your code to copy the item...
}

```