Show payment method only if shopper field is filled

[kratzi]

Hi I would like to offer a payment method only to customers who filled a special field in registration form.
As soon they enter their personal number during registration I would like to show them the payment method invoice payment.

However when the personal number is not entered the payment method should not be displayed.

I am running on VM 3.0.12  J 3.4.8

Thank you

[GJC Web Design]

simplest by javascript/jquery etc

if field filled unhide the payment section

or adapt the payment plugin but then you would need to "submit" the shopper field