var Signup = {
  duplicateFields: function(field) {
    $("account_url").value = Signup.sanitizeSubdomain(field.value); 
  },
  validateSubdomain: function(field) {
    field.value = Signup.sanitizeSubdomain(field.value);
  },
  sanitizeSubdomain: function(value) {
    return value.toLowerCase().replace(/^www\./i, "").replace(/[^-a-z0-9]/g, "");
  }
}