material validation form angular 8 code example

Example: form validation in angular material example

setPhoneValidation() {  const phoneControl = this.registerForm.get("phone");  phoneControl.setValidators([Validators.pattern("^[0-9]*$"),  Validators.required,]);this.registerForm.get("role").valueChanges.subscribe((role) => {  if (role == "jobSeeker") {    phoneControl.setValidators([Validators.pattern("^[0-9]*$"),    Validators.required,]);} else if (role == "employee") {      phoneControl.setValidators([Validators.pattern("^[0-9]*$")]);    }  phoneControl.updateValueAndValidity();});}