elm-ports-swclient.js

var channel = new BroadcastChannel("sw-messages");
var ElmPortsSWClient = {
    registration: null,
    bind: function(app) {
        app.ports.availabilityRequest.subscribe(() => {
            var available = "serviceWorker" in navigator;
            app.ports.availabilityResponse.send(available);
        });

        app.ports.registrationRequest.subscribe(() => {
            navigator.serviceWorker.register("/service-worker.js").then(
                registration => {
                    if (this.registration != null) {
                        console.log("I already have a registration :-(");
                        return;
                    }

                    this.registration = registration;
                    app.ports.registrationResponse.send("success");
                },
                err => {
                    app.ports.registrationResponse.send("error");
                }
            ).catch(x => {
                console.log(x);
            });
        });

        navigator.serviceWorker.onmessage = event => {
            app.ports.onMessageInternal.send(event.data);
        };

        app.ports.postMessageInternal.subscribe(msg => {
            if (!this.registration.active) {
                console.log("could not post msg: SW not active");
                return;
            }
            var sw = this.registration.active;
            sw.postMessage(msg);
        });

        channel.onmessage = event => {
            app.ports.onMessageInternal.send(event.data);
        };
        
        app.ports.requestPermissionInternal.subscribe(() => {
            Notification.requestPermission();
        });
    }

};