从Elm获取页面的主机名

import Browser
import Html exposing (text)


main =
  Browser.element
    { init = init
    , update = update
    , subscriptions = subscriptions
    , view = view
    }


-- Model


type alias Model =
  { hostname : String
  }


init : Model
init =
  { hostname = ""
  }


-- Msg


type Msg
  = UpdateHostname


-- Update


update : Msg -> Model -> Model
update msg model =
  case msg of
    UpdateHostname ->
      { model | hostname = Window.location.host }


-- Subscriptions


subscriptions : Model -> Sub Msg
subscriptions model =
  Sub.none


-- View


view : Model -> Html Msg
view model =
  text model.hostname