Reloads modules and widgets when corresponding AMD module is modified on the server. Uses SignalR Hub for notification. Facilitates development of widgets and singletons without the need to refresh the browser. State is captured during "unload".

reloadManager.js

define(["dojo/dom-construct", "dijit/registry"], function (domConstruct, registry) {

    return function (myHub) {
        myHub.client.reload = function (mid) {
            var mods = mid.split(",");

            // call unload on old modules
            require(mods, function () {
                var factories = Array.prototype.slice.apply(arguments);
                var state = mods.map(function (mid, i) {
                    return factories[i].unload ? factories[i].unload(mid) : {};
                });

                // call unload on old widgets
                var widgets = registry.toArray()
                    .filter(function (w) {
                        return !!w.unload;
                    })
                    .filter(function (w) {
                        return factories.some(w.isInstanceOf);
                    });

                // capture widget state
                var widgetState = widgets.map(function (w) {
                    var base = w.constructor._meta.bases[0];
                    var factoryIndex = factories.indexOf(base);
                    return {
                        state: w.unload(),
                        parentNode: w.domNode.parentNode,
                        factoryIndex: 0 <= factoryIndex ? factoryIndex : null,
                        constructor: 0 > factoryIndex ? w.constructor : null
                    };
                });

                // destroy widgets
                widgets.forEach(function (w) {
                    w.destroyRecursive();
                });

                // unload old modules if possible
                require.undef && mods.forEach(require.undef);

                // load new modules and call reload with state from prior module
                require(mods, function () {
                    var factories = arguments;
                    mods.forEach(function (mid, i) {
                        factories[i](state[i]);
                    });

                    widgetState.map(function (state) {
                        factory = state.constructor || factories[state.factoryIndex];
                        var w = new factory(state.state, domConstruct.create("div", {}, state.parentNode));
                    });

                });

            });

        };
    }

});