Domain-Driven Frontends

Domain-Driven Frontends is an important part of building production-ready single-spa systems. This lesson explains what domain-driven frontends means, how it works, and how to apply it with practical examples you can reuse.

Domain-Driven Frontends Overview

Domain-Driven Frontends is a building block you will reach for often in single-spa. It keeps related logic together and makes your intent obvious to reviewers and future maintainers.

When you learn domain-driven frontends properly, you avoid the guesswork that leads to bugs and rework. The example below shows the shape you will use in most real single-spa projects.

import { registerApplication, start } from 'single-spa';

registerApplication({
  name: '@org/app',
  app: () => System.import('@org/app'),
  activeWhen: ['/app'],
});

start();

single-spa orchestrates multiple framework apps on one page through a root config.

Domain-Driven Frontends Example

registerApplication({
  name: '@org/app',
  app: () => System.import('@org/app'),
  activeWhen: ['/app'],
});
start();

Start from a minimal Domain-Driven Frontends example and grow it only as needed.
Keep configuration explicit so Domain-Driven Frontends behaves the same in every environment.
Name things clearly so teammates understand your Domain-Driven Frontends at a glance.
Add tests around Domain-Driven Frontends early to lock in expected behaviour.

Single-SPA Cheatsheet

Core single-spa APIs related to domain-driven frontends.

API	Example	Purpose
registerApplication	`registerApplication({ name, app, activeWhen })`	Register a micro frontend
activeWhen	`activeWhen: ['/checkout']`	Route ownership
start	`start()`	Begin routing
bootstrap	`export async function bootstrap()`	One-time setup
mount	`export async function mount(props)`	Render the app
unmount	`export async function unmount(props)`	Clean up the app
import map	`systemjs-importmap`	Locate app bundles

How Domain-Driven Frontends Works in Single-SPA

Domain-Driven Frontends is part of how single-spa lets multiple applications — even in different frameworks — coexist on one page. A root config registers each app and controls when it is active.

single-spa orchestrates multiple framework apps on one page through a root config.

A root config registers apps and calls start().
Each app exports bootstrap, mount, and unmount lifecycles.
activeWhen decides which routes each app owns.
Import maps resolve each app's bundle at runtime.

Practical Guidance for Domain-Driven Frontends

For reliable micro frontends, domain-driven frontends should isolate failures and keep shared state minimal. Let each team own its app end to end while agreeing on a few shared contracts.

Concern	Recommendation
Isolation	One app's crash should not break others
Shared state	Prefer shared utility modules over globals
Routing	Keep activeWhen rules explicit and non-overlapping
Deployment	Release via import-map updates per app

Common Mistakes

Copying domain-driven frontends snippets without understanding what each line does.
Skipping error handling and edge cases when wiring up domain-driven frontends.
Leaving domain-driven frontends untested, so regressions slip into production.
Over-engineering domain-driven frontends before you actually need the extra flexibility.

Key Takeaways

Domain-Driven Frontends is a core part of working effectively with single-spa.
Start small and keep domain-driven frontends focused on a single responsibility.
Apply consistent patterns so domain-driven frontends scales across your project.
Test and document domain-driven frontends to keep it maintainable over time.

Pro Tip

Pair domain-driven frontends with automated tests from day one. It is far cheaper to catch single-spa regressions in CI than in production.