Backbone routing doesn't work when converted to TypeScript

Question

I'm trying to convert a basic Backbone.js router declaration to TypeScript.

var AppRouter = Backbone.Router.extend({
    routes: {
        "*actions": "defaultRoute"
    },

    defaultRoute: function () {
        document.write("Default Route Invoked");
    }
});

var app_router = new AppRouter();

Backbone.history.start();

My converted code is the following which doesn't work:

class AppRouter extends Backbone.Router {
    routes = {
        "*actions": "defaultRoute"
    }

    defaultRoute() {
        document.write("Default Route Invoked");
    }
}

var app_router = new AppRouter();

Backbone.history.start();

I get no compile time or runtime errors but the code does not function. Why?

Answer 1

Add all initialized fields in the constructor and make a call to super at the end:

class AppRouter extends Backbone.Router {

    routes: any;
    constructor(options?: Backbone.RouterOptions) {

        this.routes = {
            "*actions": "defaultRoute"
        }

        super(options);
    }

    initialize() {
        // can put more init code here to run after constructor
    }

    defaultRoute() {
        document.write("Default Route Invoked");
    }
}

var app_router = new AppRouter();

Backbone.history.start();