Guidelines for Packages

List exports explicitly

Every package in this monorepo should have an index.ts file in the src/ directory. Any symbols that this file exports will be usable by consumers.

It is tempting to save time by re-exporting all symbols from one or many files by using the "wildcard" or "barrel" export syntax:

🚫

export * from './foo';
export * from './bar';

However, using this syntax is not advised for the following reasons:

• Barrel exports make it difficult to understand the public surface area of a package at a glance. This is nice for general development, but is especially important for debugging when sorting through previously published versions of the package on a site such as npmfs.com.
• Any time a new export is added to one of these files, it will automatically become an export of the package. That may sound like a benefit, but this makes it very easy to increase the surface area of the package without knowing it.
• Sometimes it is useful to export a symbol from a file for testing purposes but not expose it publicly to consumers. With barrel exports, however, this is impossible.

Instead of using barrel exports, name every export explicitly:

✅

export { A } from './foo';
export type { B } from './foo';
export { C } from './bar';
export { C } from './bar';
export type { D } from './bar';