Estoy tratando de agregar días seleccionados del menú desplegable. Pero las fechas que surgen después de agregar se remontan a 1700. ¿Qué estoy haciendo mal aquí?

 selectedDays: number = 0; //event handler for the select element's change event selectDaystoadd (event: any) { //update the ui this.selectedDays = event.target.value; console.log(this.selectedDays); } formatDateField(event: Date, formControl: string) { this.form .get(formControl) .patchValue( this.datePipe.transform(event.getTime() + this.selectedDays, "yyyy-MM-dd'T'HH:mm:ss") ); console.log(event); }

Código HTML..

 <label>Date</label> <input id="input--payout-date" class="form-control" formControlName="payoutDate" [owlDateTime]="payoutDate" (dateTimeInput)="formatDateField($event.value, 'payoutDate')" [owlDateTimeTrigger]="payoutDate" /> <owl-date-time [pickerType]="'calendar'" #payoutDate></owl-date-time> <label>Add days to date</label> <select (change)="selectDaystoadd($event)"> <option value="0">0</option> <option value="20">+20</option> <option value="50">+30</option> <option value="90">+90</option> </select>