Add a "." between the subdomain and domain names, only when needed.

spago.dhall

@@ -24,6 +24,7 @@
   , "prelude"
   , "profunctor"
   , "strings"
+  , "stringutils"
   , "transformers"
   , "tuples"
   , "uint"

src/App/DNSManagerDomainsInterface.purs

@@ -15,6 +15,8 @@ import Prelude
 
 import Bulma as Bulma
 
+import Data.String.Utils (endsWith)
+-- import Data.String.CodeUnits as DSCU
 import Halogen.HTML.Events as HHE
 import Control.Monad.Except (runExcept)
 import Control.Monad.State (class MonadState)
@@ -344,7 +346,7 @@ handleAction = case _ of
     H.liftEffect $ Event.preventDefault ev
 
     { wsInfo, newDomainForm } <- H.get
-    let new_domain = newDomainForm.new_domain <> newDomainForm.selected_domain
+    let new_domain = build_new_domain newDomainForm.new_domain newDomainForm.selected_domain
 
     case wsInfo.connection, new_domain of
       Nothing, _ ->
@@ -461,6 +463,12 @@ handleAction = case _ of
         , "]"
         ]
 
+build_new_domain :: String -> String -> String
+build_new_domain sub tld
+  | sub == ""        = "." <> tld
+  | endsWith "." sub = sub <> tld
+  | otherwise        = sub <> "." <> tld
+
 sendArrayBuffer :: WS.WebSocket -> ArrayBuffer -> Effect Unit
 sendArrayBuffer = WS.sendArrayBuffer