Bootstrap Lifecycle

Bootstrap Lifecycle Overview

Bootstrap Lifecycle lets you structure single-spa work so it stays readable, testable, and easy to scale. Instead of ad-hoc code, you follow a clear pattern that other developers can recognise immediately.

The key is to keep bootstrap lifecycle focused and predictable. Start from the minimal example here, then layer in only the complexity your feature actually needs.

export async function bootstrap(props) {
  // one-time setup
}

export async function mount(props) {
  // render the app into props.domElement
}

export async function unmount(props) {
  // tear down and clean up
}

Every single-spa application exports bootstrap, mount, and unmount lifecycle functions.

Bootstrap Lifecycle Example

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

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

Single-SPA Cheatsheet

Core single-spa APIs related to bootstrap lifecycle.

How Bootstrap Lifecycle Works in Single-SPA

Bootstrap Lifecycle 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.

Every single-spa application exports bootstrap, mount, and unmount lifecycle functions.

• 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 Bootstrap Lifecycle

For reliable micro frontends, bootstrap lifecycle 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 bootstrap lifecycle.
• Leaving bootstrap lifecycle untested, so regressions slip into production.
• Over-engineering bootstrap lifecycle before you actually need the extra flexibility.
• Ignoring documentation, which makes bootstrap lifecycle hard for the next developer to change.

Key Takeaways

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