Application Errors

Application Errors Overview

At its core, application errors 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 application errors 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.

Application Errors Example

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

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

Single-SPA Cheatsheet

Core single-spa APIs related to application errors.

How Application Errors Works in Single-SPA

Application Errors 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 Application Errors

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

Key Takeaways

• Application Errors is a core part of working effectively with single-spa.
• Start small and keep application errors focused on a single responsibility.
• Apply consistent patterns so application errors scales across your project.
• Test and document application errors to keep it maintainable over time.