Framework Parcels

Framework Parcels Overview

At its core, framework parcels 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 framework parcels pays off across the whole codebase: fewer surprises, easier testing, and smoother onboarding. The snippet below is a solid starting point.

import Parcel from 'single-spa-react/parcel';

<Parcel
  config={() => System.import('@org/product-card')}
  wrapWith="div"
  productId={id}
/>

Parcels let one framework render a component owned by another, independent of routing.

Framework Parcels Example

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

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

Single-SPA Cheatsheet

Core single-spa APIs related to framework parcels.

How Framework Parcels Works in Single-SPA

Framework Parcels 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.

Parcels let one framework render a component owned by another, independent of routing.

• 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 Framework Parcels

For reliable micro frontends, framework parcels 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

• Skipping error handling and edge cases when wiring up framework parcels.
• Leaving framework parcels untested, so regressions slip into production.
• Over-engineering framework parcels before you actually need the extra flexibility.
• Ignoring documentation, which makes framework parcels hard for the next developer to change.

Key Takeaways

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