Angular form validations triggered at field change

this.form.controls[this.FIELDS.field1].markAsTouched(); // if not touched, it won't validate although it has a value

this.form.controls[this.FIELDS.field].valueChanges.subscribe(() => {

            this.form.controls[this.field1].updateValueAndValidity();

            this.form.controls[this.field2].updateValueAndValidity();

});