Efforts were made to introduce ESM builds in node-cron. However, they were not fully completed.

What was done

• Enabled easier local testing with arethetypeswrong
  • Added *.tgz to .gitignore to ignore the file that npm pack outputs
  • Changed prepublishOnly to prepack to build the package before packing it - not necessarily with the intention of immediately publishing it
• Rewrote all import paths to actually be ESM compatible (/some-module.js -> ./some-module.js, ./some-directory -> ./some-directory/index.js)
• Build changes
  • Rewrote type, types, exports fields in package.json
  • Reworked build commands to add a secondary package.json in /dist/cjs guiding Node.js module resolution algorithm
• TypeScript changes
  • simplified setup: default TypeScript config is now ESM, CJS config inherits from it and has CJS-specific overrides
  • verbatimModuleSyntax setting was enabled to prevent TypeScript from creating empty modules, like dist/esm/tasks/scheduled-task.js:
    

What still needs attention

• Path resolving in startDaemon
• Dual testing on built code: CJS and ESM

Before

/dist/esm still contains code compiled to CJS:

https://www.npmjs.com/package/node-cron?activeTab=code

and arethetypeswrong reports CJS default export on ESM environments:

https://arethetypeswrong.github.io/?p=node-cron%404.2.1

After

/dist/esm contains ESM code:

and arethetypeswrong CLI reports no issues with module resolution: