feat(browser): build a dedicated version for the browser

BREAKING CHANGE: This PR change of the internal directory structure of the exported code. The previous code has move from the `dist/` into the `dist/esm` directory (but remender that we do not avice you to do this 🤓)

package.json

@@ -2,16 +2,23 @@
   "name": "react-element-to-jsx-string",
   "version": "13.0.0",
   "description": "Turn a ReactElement into the corresponding JSX string.",
-  "main": "dist/index.js",
+  "main": "dist/cjs/index.js",
+  "module": "dist/esm/index.js",
+  "browser": "dist/cjs/index.js",
   "scripts": {
-    "build":
-      "babel ./src/ --ignore=*.spec.js --source-maps --out-dir ./dist/ && flow-copy-source -v --ignore=*.spec.js src/ dist/",
-    "lint": "node_modules/.bin/eslint .",
+    "clean": "npm run esm:clean && npm run cjs:clean",
+    "prebuild": "npm run clean",
+    "build": "npm run esm:build && npm run cjs:build",
+    "esm:build":
+      "babel ./src/ --ignore=*.spec.js --source-maps --out-dir ./dist/esm && flow-copy-source -v --ignore=*.spec.js src/ dist/esm",
+    "esm:clean": "rm -rf ./dist/esm/*",
+    "cjs:build": "rollup --config rollup.config.js",
+    "cjs:clean": "rm -rf ./dist/cjs/*",
+    "lint": "eslint .",
     "lint:fix": "npm run lint -- --fix",
     "flow": "flow",
     "precommit": "lint-staged",
     "prepublish": "npm run build",
-    "prebuild": "mkdir -p dist && rm -rf ./dist/*",
     "prettier:fix":
       "prettier --write --single-quote --trailing-comma es5 \"{src/**/*.js,package.json}\"",
     "test": "jest && npm run lint && npm run flow",
@@ -38,6 +45,7 @@
     "babel-cli": "6.26.0",
     "babel-eslint": "8.0.2",
     "babel-jest": "21.2.0",
+    "babel-plugin-external-helpers": "^6.22.0",
     "babel-preset-es2015": "6.24.1",
     "babel-preset-flow": "6.23.0",
     "babel-preset-react": "6.24.1",
@@ -63,7 +71,15 @@
     "prettier": "1.8.2",
     "react": "16.1.0",
     "react-dom": "16.1.0",
-    "react-test-renderer": "16.1.0"
+    "react-test-renderer": "16.1.0",
+    "rollup": "^0.51.3",
+    "rollup-plugin-babel": "^3.0.2",
+    "rollup-plugin-commonjs": "^8.2.6",
+    "rollup-plugin-flow": "^1.1.1",
+    "rollup-plugin-node-builtins": "^2.1.2",
+    "rollup-plugin-node-globals": "^1.1.0",
+    "rollup-plugin-node-resolve": "^3.0.0",
+    "rollup-plugin-sourcemaps": "^0.4.2"
   },
   "peerDependencies": {
     "react": "^0.14.8 || ^15.0.1 || ^16.0.0"

rollup.config.js

@@ -0,0 +1,49 @@
+import babel from 'rollup-plugin-babel';
+import commonjs from 'rollup-plugin-commonjs';
+import flow from 'rollup-plugin-flow';
+import resolve from 'rollup-plugin-node-resolve';
+import builtins from 'rollup-plugin-node-builtins';
+import globals from 'rollup-plugin-node-globals';
+
+export default {
+  input: 'src/index.js',
+  output: {
+    file: 'dist/cjs/bundle.js',
+    format: 'cjs',
+  },
+  sourcemap: true,
+  plugins: [
+    babel({
+      babelrc: false,
+      exclude: 'node_modules/**', // only transpile our source code
+      presets: [
+        [
+          'es2015',
+          {
+            modules: false,
+          },
+        ],
+        'stage-2',
+        'react',
+        'flow',
+      ],
+      plugins: ['external-helpers'],
+      externalHelpers: true,
+    }),
+    resolve({
+      module: true,
+      jsnext: true,
+      main: true,
+      browser: true,
+    }),
+    commonjs({
+      sourceMap: true,
+      namedExports: {
+        react: ['isValidElement'],
+      },
+    }),
+    globals(),
+    builtins(),
+    flow(),
+  ],
+};