Angular, Disable submit button using [disabled] to check form validity

Since you have your formGroup object, you can disable the button if form01 is not valid

<!--component.html-->
    <div>
      <form [formGroup]="form01">
        email:<input type="text" name="email" formControlName="email" required/> gender:
        <input type="radio" name="gender" formControlName="gender" value="male"> male<br>
        <input type="radio" name="gender" formControlName="gender" value="female"> female<br> DoB:
        <my-date-picker name="DoB" [options]="myDatePickerOptions" formControlName="DoB" required></my-date-picker>

    <button type="submit" [disabled]="!form01.valid" (click)="functionForm01()">Click</button>

      </form>
    </div>

You can enable/disable the button by checking the validity of your form:

<button type="submit" [disabled]="!disableBtn">Click</button>

Inside your component:

let disableBtn = false;
this. form01.valueChanges 
            .subscribe((changedObj: any) => {
                 this.disableBtn = this. form01.valid;
            });

Or via HTML:

<button type="submit" [disabled]="!form01.valid" (click)="functionForm01()">Click</button>