JAVASCRIPT

dynamic set required in angular using formcontrol

onAddValidationClick(){
    this.formGroup.controls["firstName"].setValidators(Validators.required);
    this.formGroup.controls["firstName"].updateValueAndValidity();
}

onRemoveValidationClick(){
    this.formGroup.controls["firstName"].clearValidators();
    this.formGroup.controls["firstName"].updateValueAndValidity();
}