How I register routers in Express

Jul 27, 2023 • 2 min read

When people use Express, they typically write a couple endpoints and call it a day.

But suppose that you’ve decided to create a larger project with Express and you wanted to utilize the Router object that Express provides to break out your project into little apps like Django. You might end up with dozens of directories that contain app-level logic and you’ll find yourself registering all these routes in your index.js files one-by-one. Something like the following:

app.use("/...", ...)
app.use("/...", ...)
app.use("/...", ...)
app.use("/...", ...)
app.use("/...", ...)
app.use("/...", ...)
app.use("/...", ...)
// ... and the list goes on.

Personally, I didn’t like that this was how I was registering routes. So I created a Record where the key was the API endpoint and the value was the Router object in a separate file called src/lib/routes.js. It looked like the following:

const ROUTES = {
  [...]: someRouter,
  // This would keep growing
};

Given that I have them all registered in a separate common file, I also built a function that would just register the routes in the same file.

/**
 * `registerRoutes` makes sure that all our routers are
 * registered with the Express app.
 *
 * @param {import("express").Express} app
 */
export function registerRoutes(app) {
  Object.entries(ROUTES).forEach(([url, router]) => {
    app.use(url, router);
  });
}

Now instead of having to add a new call app.use("/...", ...) every time I create a new app to register for my API, I can just add the key-value pair to the Record. In my index.js file, we’d just have one call to registerRoutes(app).

In reality, there’s no real performance benefit. My code just looks less stupid now.