start() Method

start() Method Overview

At its core, start() method is about doing one thing well inside your single-spa project. Once you understand the pattern, you can apply it consistently across features and teams.

Good start() method pays off across the whole codebase: fewer surprises, easier testing, and smoother onboarding. The snippet below is a solid starting point.

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.

start() Method Example

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

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

Single-SPA Cheatsheet

Core single-spa APIs related to start() method.

How start() Method Works in Single-SPA

start() Method 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 start() Method

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

Common Mistakes

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

Key Takeaways

• start() Method is a core part of working effectively with single-spa.
• Start small and keep start() method focused on a single responsibility.
• Apply consistent patterns so start() method scales across your project.
• Test and document start() method to keep it maintainable over time.