Extracting and breaking Down a date from a Material Date picker

So im trying to figure out how I can "Properly" separate the dates im getting from the Date range selector.

I've managed to separate them into a start and end value but Id need to more then likely use some kind of regex to separate the dates into a D/M/Y because I have 3 variables I need to fill as later on I need to do calculations with the years and one value is terrible for that. Curious if anyones got any ideas about this

Outputs:

1/1/2021 || 1/8/2021

    <mat-form-field appearance="fill">
        <mat-label>Enter a date range</mat-label>
        <mat-date-range-input [formGroup]="range" [rangePicker]="picker">
          <input style="position: relative;" #Startz matStartDate formControlName="start" placeholder="Start date">
          <input style="position: relative;"  #Endz matEndDate formControlName="end" placeholder="End date">
        </mat-date-range-input>
        <mat-datepicker-toggle matSuffix [for]="picker"></mat-datepicker-toggle>
        <mat-date-range-picker #picker></mat-date-range-picker>
      
        <mat-error *ngIf="range.controls.start.hasError('matStartDateInvalid')">Invalid start date</mat-error>
        <mat-error *ngIf="range.controls.end.hasError('matEndDateInvalid')">Invalid end date</mat-error>
      </mat-form-field>
      
 
     <div class="">
        <input type="text" class="" placeholder="info" #info required>
     </div>
    
     <button style="margin-right:10px;" type="button" class="btn googleBtn" value="Log In" (click)="createEntry(Startz.value, Endz.value, info.value)">Create Entry</button>

createEntry(startDate, endDate,  info: string){
      alert(startDate + endDate);
  }

export class Entry {
    id: string;
    surname: string;
    color: string;
    startDate: Startdate;
    endDate: Enddate;
    info: string;
    status: boolean;
}

export class Startdate{
    day: number;
    month: number;
    year: number;
}

export class Enddate{
    day: number;
    month: number;
    year: number;
}

This is what ive done so far but there should surely be a better solution for this:

    var value = startDate;
    var day = value.substring(0,1);
    var month = value.substring(2,3);
    var year = value.substring(4,8);
    var str = "{Day:" + day + ",month:" + month + ",year:" + year + "}";
      alert(str);

The issue with this way is that asoon as u end up with double digit days/months ect it breaks