quicktype-core: ship an ESM build with an 'exports' map (currently CJS-only)

[schani]

Issue Type

Feature request / packaging: quicktype-core ships CommonJS only, no ESM build or exports map

Context (Environment, Version, Language)

CLI, npm, or app.quicktype.io: npm package quicktype-core
Version: 24.0.0

Description

quicktype-core@24.0.0 publishes only a CommonJS build:

{
  "main": "dist/index.js",
  "types": "dist/index.d.ts"
}

• No "exports" map
• No "module" / ESM entry point
• No "type" field (defaults to CommonJS)

To be fair about the current state: in my testing this causes no runtime breakage on Node 20/22/24 — named imports like import { quicktype, InputData } from "quicktype-core" work from "type": "module" projects via Node's CJS interop (cjs-module-lexer), and moduleResolution: nodenext typechecks correctly. So this is a modernization request, not a "it's broken" report.

What consumers do lose without a real ESM build:

• Tree-shaking: bundlers (esbuild, Rollup, webpack) treat the CJS build as opaque, so browser/edge consumers pull in the whole library even when using a single target language.
• Conditional exports: no "exports" map means no way to route browser vs. node entry points (relevant since quicktype-core already depends on browser-or-node and has browser-specific code paths).
• Named-import interop relies on cjs-module-lexer heuristics rather than being guaranteed by the module format.

Expected Behaviour / Output

Dual CJS/ESM publish (or ESM-only, given engines: ">=20"), with an "exports" map along the lines of:

{
  "exports": {
    ".": {
      "types": "./dist/index.d.ts",
      "import": "./dist/esm/index.js",
      "require": "./dist/index.js"
    }
  }
}

Current Behaviour / Output

CJS-only as described above.

Found while testing the 24.0.0 release on Node 20/22/24 in both CommonJS and "type": "module" TypeScript projects.

[schani]

Verified fixed in quicktype-core@24.0.1:

• Proper exports map with import → ./dist/esm/index.js and require → ./dist/index.js, each with its own types condition.
• dist/esm/ is genuine ESM and ships its own {"type": "module"} package.json, so there's no misparsing hazard.
• import.meta.resolve("quicktype-core") from a "type": "module" project resolves to dist/esm/index.js — the real ESM build, not CJS interop.
• All runtime tests pass for both builds on Node 20.19.4, 22.23.1, and 24.6.0.

One heads-up for bundler users (not a quicktype bug): esbuild --format=esm --platform=node bundles throw Dynamic require of "process" is not supported because the yaml dependency's import entry wraps its CJS core. The standard createRequire banner fixes it. PR incoming to mention this in the README.