Moving to ESM from CJS with Anthony Fu

This episode explores the ongoing transition in the JavaScript ecosystem from CommonJS (CJS) modules to the newer ECMAScript Modules (ESM) standard. Against the backdrop of this shift, the discussion centers on the challenges and benefits of adopting ESM, particularly for package maintainers. More significantly, the interview delves into the complexities of maintaining dual-format packages (supporting both CJS and ESM), highlighting the technical hurdles and potential for bugs. For instance, differences in export mechanisms between CJS and ESM necessitate workarounds and can lead to inconsistencies in type definitions. The conversation then pivots to a newly developed tool, `node-modules-inspector`, designed to visualize package dependencies and identify potential issues, including outdated or vulnerable packages. Ultimately, the episode suggests that while migrating to ESM-only might initially seem daunting, the availability of tools and the increasing support for ESM in modern build systems make it a worthwhile endeavor for long-term maintainability and compatibility. What this means for the future of JavaScript development is a more streamlined and efficient ecosystem, although some legacy systems may require significant upgrades or even rewrites.