Refactor `package.json` exports to be compatible with Typescript 4.7+

fixPackageJsonExports.mjs

// @ts-check

import path from 'path'
import { readFile, writeFile } from 'fs/promises'
import glob from 'tiny-glob'

/**
 * @typedef {object} LegacyExportField
 * @property {string} [types]
 * @property {string} [import]
 * @property {string} [require]
 */

/**
 * @typedef {object} ExportFieldEntry
 * @property {string} [types]
 * @property {string} [default]
 */

/**
 * @typedef {object} ExportField
 * @property {ExportFieldEntry | string} [import]
 * @property {ExportFieldEntry | string} [require]
 */

/**
 * @typedef {object} PackageJson
 * @property {string} [name]
 * @property {Record<string, LegacyExportField> | Record<string, ExportField>} [exports]
 */

async function fixPackageJsonExports() {
  let packageJsonList = await glob('**/package.json')

  for (const packageJsonPath of packageJsonList) {
    try {
      const rootDir = '.'
      const pkgPath = path.join(rootDir, packageJsonPath)
      const pkgUrl = new URL(pkgPath, import.meta.url)

      /** @type {PackageJson} */
      const pkg = JSON.parse(await readFile(pkgUrl, { encoding: 'utf8' }))

      // skip projects without mapped exports
      if (!pkg.exports || Object.keys(pkg.exports).length === 0) continue

      for (const key of Object.keys(pkg.exports)) {
        const entry = pkg.exports?.[key]

        if (entry && 'types' in entry) {
          /** @type {LegacyExportField} */
          const field = entry

          pkg.exports[key] = {}
          
          if (field.types) {
            // the entry has types definitions

            if (field.import) {
              pkg.exports[key].import = { types: field.types, default: field.import }
            }

            if (field.require) {
              pkg.exports[key].require = { types: field.types, default: field.require }
            }
          } else {
            // the entry is withou types definitions           

            if (field.import) {
              pkg.exports[key].import = field.import
            }

            if (field.require) {
              pkg.exports[key].require = field.require
            }
          }
        }
      }

      const content = JSON.stringify(pkg, null, 2) + '\n'
      await writeFile(pkgUrl, content, { encoding: 'utf8', flag: 'w' })
    } catch (e) {
      console.log(e)
    }
  }
}

fixPackageJsonExports()

Since version 4.7 TypeScript officially supports the package.json exports field.

If you have projects that are using Node exports, it may be that your exports are something like:

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

This script helps to refactor your exports to be compatible with TypeScript 4.7+

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

The scripts will work on a single project or in a mono-repo.
I hope this will save some time for other people having many TypeScript projects with a lot of exports ;)