Sure, script below:
if (mbox.name == 'dashboard_header_banner') {
var signUpDate = mbox.param('registration_date'); //"yyyy-mm-dd"
var day = signUpDate.split("-")[2];
var month = signUpDate.split("-")[1];
var year = signUpDate.split("-")[0];
var dateText = year + month + day;
var date = parseInt(dateText);
return date
}
The 'E7' just means x10^7. It's shorthand; the date format I've used yields a number over 20 million, and it doesn't like having that many digits. It's still technically a number.
I did think it might be returning a string, though. Thought that it was possible to use numbers though, as the 'greater than' option is available to use.