ng_for_in-2.ts

ngOnChanges(changes: SimpleChanges): void {
  if ('ngForIn' in changes) {
    this.ngForOf = Object.keys(this.ngForIn);

    const currentValue: any[] = Object.keys(changes['ngForIn'].currentValue);
    const previousValue: any[] = Object.keys(changes['ngForIn'].previousValue);
    changes['ngForOf'] =  new SimpleChange(previousValue, currentValue);

    super.ngOnChanges(changes);
  }
}