Elm Language Ports (JS interop) Outgoing
Example
Outgoing ports are used as Commands, that you return from your update function.
Elm side
Define outgoing port:
port output : () -> Cmd msg
In this example we send an empty Tuple, just to trigger a subscription on the JavaScript side.
To do so, we have to apply output function with an empty Tuple as argument, to get a Command for sending the outgoing data from Elm.
update msg model =
case msg of
TriggerOutgoing data ->
( model, output () )
JavaScript side
Initialize the application:
var root = document.body;
var app = Elm.Main.embed(root);
Subscribe to a port with a corresponding name:
app.ports.output.subscribe(function () {
alert('Outgoing message from Elm!');
});
Note
As of 0.17.0, immediate outgoing message to JavaScript from your initial state will have no effect.
init : ( Model, Cmd Msg )
init =
( Model 0, output () ) -- Nothing will happen
See the workaround in the example below.
