Shiver My Timbers! Migrating yargs to ECMAScript Modules
summary
Yargs migrates to dual ESM+CJS so existing users keep working while modern platforms can import it, using a TypeScript → ES2020 build plus Rollup to emit a bundled CommonJS file and an .mjs entry via an exports map. The process increases package size and CI complexity, introduces webpack interoperability bugs, and forces fiddly exports-map and extension workarounds, but it runs in browsers and Deno, shows minimal regressions, and supports 24,000 dependents with 10 million downloads a week via rollup + TypeScript build producing index.cjs/index.mjs.
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chapters (14)
- 0:00Start
- 2:08What we'll be covering
- 3:51Not a new concept
- 4:08ServerJS, Jan 2009
- 5:30Asynchronous Module Definition, Sep 2010
- 9:52Writing Pure ESM
- 10:45Writing dual ESM/CommonJS
- 12:53Approaches one could take
- 14:34yargs' new build step
- 15:47rollup.config.cjs
- 16:21tsconfig.json
- 16:40package.json
- 19:44In Conclusion...
- 23:1607 Links/Bibliography
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