Strategies for server-side rendering of asynchronously initialized React.js components

If you use react-router, you can just define a willTransitionTo methods in components, which gets passed a Transition object that you can call .wait on.

It doesn't matter if renderToString is synchronous because the callback to Router.run will not be called until all .waited promises are resolved, so by the time renderToString is called in the middleware you could have populated the stores. Even if the stores are singletons you can just set their data temporarily just-in-time before the synchronous rendering call and the component will see it.

Example of middleware:

var Router = require('react-router');
var React = require("react");
var url = require("fast-url-parser");

module.exports = function(routes) {
    return function(req, res, next) {
        var path = url.parse(req.url).pathname;
        if (/^\/?api/i.test(path)) {
            return next();
        }
        Router.run(routes, path, function(Handler, state) {
            var markup = React.renderToString(<Handler routerState={state} />);
            var locals = {markup: markup};
            res.render("layouts/main", locals);
        });
    };
};

The routes object (which describes the routes hierarchy) is shared verbatim with client and server