Real compose function implementation (composing middlewares)

basic-express.js

var app = {
    middlewares: [],
    use(fn) {
        this.middlewares.push(fn)
    },
    compose(middleware) {
        return function (next) {
            return dispatch(0)
            function dispatch(i) {
                let fn = middleware[i]
                if (!fn) {
                    return
                }
                fn(function next() {
                    return dispatch(i + 1)
                })
            }
        }
    },
    start() {
        this.compose(this.middlewares)();
    }

}
var app1 = (subapp) => {
    console.log('start', 1);
    subapp();
    console.log('finish', 5);
}
var app2 = (subapp) => {
    console.log(2);
    subapp();
    console.log(4);
}
var app3 = (subapp) => {
    subapp()
    console.log(3);
}

app.use(app1)
app.use(app2)
app.use(app3)
app.start()