fix(package): use ESM build for browser entry

[rbardini]

Summary

The browser field points to the CommonJS build (dist/cjs/index.js). Browser-targeting bundlers that read browser therefore resolve the CJS build, which can break default-export interop. For example, building a Storybook 11 addon with Vite/Rolldown that imports this package throws:

Uncaught TypeError: import_cjs.default is not a function

and, once the CJS build is inlined, its require('react') becomes a runtime require that fails in the browser:

Uncaught Error: Calling `require` for "react" in an environment that doesn't expose the `require` function.

Relates to rbardini/storybook-addon-playroom#88.

Change

• Point browser at the ESM build (dist/esm/index.js).
• Add an exports map so modern resolvers use the ESM build for import/browser and the CJS build for require, while keeping main/module/types for older tooling.

"main": "dist/cjs/index.js",
"module": "dist/esm/index.js",
"browser": "dist/esm/index.js",
"types": "index.d.ts",
"exports": {
  ".": {
    "types": "./index.d.ts",
    "browser": "./dist/esm/index.js",
    "import": "./dist/esm/index.js",
    "require": "./dist/cjs/index.js",
    "default": "./dist/esm/index.js"
  },
  "./package.json": "./package.json"
}

Note

Adding exports encapsulates the package: deep imports such as react-element-to-jsx-string/dist/cjs/index.js will no longer resolve. Happy to expose those subpaths if you consider them part of the public API.

Verification

Resolution checked locally with Node (no build changes needed):

• require('react-element-to-jsx-string') → dist/cjs/index.js
• import 'react-element-to-jsx-string' → dist/esm/index.js
• import with --conditions=browser → dist/esm/index.js
• require('react-element-to-jsx-string/package.json') → resolves
• TypeScript (moduleResolution: nodenext) resolves index.d.ts

[codacy-production]

Up to standards ✅

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