Attempt to implement the route resolver concept as a component

mithril-route-resolver-2.js

// API:
// `m(RouteResolver, {onmatch(path), render(Comp)}) -> Component`
//
// Note: this is all in pure ES5
//
// Assumed extensions:
// - `m.route.default()` - Get the default route

var RouteResolver = {
    oninit: function (vnode) {
        "use strict"
        function set(comp) {
            vnode.state.comp = comp || "div"
        }
        function bail(e) {
            m.route.set(m.route.default(), null, {replace: true})
            throw e
        }
        try {
            var request = vnode.attrs.onmatch(m.route.get())
            if (request == null || typeof request.then !== "function") {
                set(request)
            } else {
                Promise.resolve(request).then(set, bail).then(m.redraw)
            }
        } catch (e) {
            bail(e)
        }
    },

    view: function (vnode) {
        "use strict"
        if (vnode.state.comp == null) return []
        return vnode.attrs.render(vnode.state.comp)
    }
}