Angular 4 Form Validators - minLength & maxLength does not work on field type number

Question

I am trying to develop a contact form, I want user to enter phone number values between length 10-12.

Notably same validation is working on Message

Answer 1

Keep and just transform the int values to strings.

const phoneControl: FormControl = this.myForm.controls.phone;

// Do not forget to unsubscribe

phoneControl.valueChanges.subscribe(v => {

  // When erasing the input field, cannot read toString() of null, can occur
  phoneControl.setValue((v && v.toString()) || null, { emitEvent: false });
});