Fastify Faux Modules Testing

• About
• Get Started
• Comments

About

Repository created to address fastify/fastify#2404.

Get Started

1. cd csj or cd esm
2. npm i
3. npm start
4. Test csj folder build using http://127.0.0.1:8000, and http://127.0.0.1:9000 for the esm folder.

Comments

• I have created two folders to highlight how TypeScript behaves when esModuleInterop is either true or false.
  • esModuleInterop is set to FALSE for the csj (CommonJS) folder and default imports are done using import * as defaultModule from 'module'.
  • esModuleInterop is set to TRUE for the esm (ES Modules) folder and default imports are done using import defaultModule from 'module'.
• I locked fastify and plugin versions to versions that match the problem being discussed in afore-mentioned GitHub issue.
• For csj folder I copied the types for all 4 plugins used into the typings folder and ensured the default export is done using the export = form because export default does not work when "esModuleInterop": false.
  • For fastify-cookie I also modified the types to move the named exports into a declared namespace (declare namespace fastifyCookie {...}).
  • For fastify-session I also had to modify the types (copied from here) because installed types are not compatible with fastify v3.
  • For fastify-websocket I copied the types from this pull request: fastify/fastify-websocket#73
• For the esm folder I used the official types because they use the export default form which works with "esModuleInterop": true.

IMPORTANT to note that the fastify-session import in the esm folder uses the same types from the csj folder (see paths property in ./esm/tsconfig.json). The point of this is to show that export = works regardless if esModuleInterop is true or false, whilst export default works on when esModuleInterop is true.