Switch the build process to rollup.js

Makes the minified UMD build 1.2kb smaller

.eslintrc

@@ -28,5 +28,12 @@
         },
       },
     },
+    {
+      "files": "rollup.config.js",
+      "parserOptions": {
+        "ecmaVersion": 2019,
+        "sourceType": "module",
+      },
+    },
   ],
 }

package.json

@@ -34,22 +34,24 @@
     "lint": "eslint .",
     "test": "npm run tests-only",
     "tests-only": "jest",
-    "umd": "NODE_ENV=development browserify index.js -t loose-envify --standalone PropTypes -o prop-types.js",
-    "umd-min": "NODE_ENV=production browserify index.js -t loose-envify -t uglifyify --standalone PropTypes  -p bundle-collapser/plugin -o | uglifyjs --compress unused,dead_code -o prop-types.min.js",
-    "build": "yarn umd && yarn umd-min",
+    "build": "rollup -c",
     "prepublish": "not-in-publish || yarn build"
   },
   "devDependencies": {
+    "babel-core": "6",
     "babel-jest": "^19.0.0",
     "babel-preset-react": "^6.24.1",
-    "browserify": "^16.5.0",
-    "bundle-collapser": "^1.3.0",
     "eslint": "^6.3.0",
     "in-publish": "^2.0.0",
     "jest": "^19.0.2",
+    "loose-envify": "^1.4.0",
     "react": "^15.5.4",
-    "uglifyify": "^5.0.2",
-    "uglifyjs": "^2.4.11"
+    "rollup": "^1.32.1",
+    "rollup-plugin-babel": "3",
+    "rollup-plugin-commonjs": "^9.3.4",
+    "rollup-plugin-node-resolve": "^2.1.1",
+    "rollup-plugin-replace": "^2.2.0",
+    "rollup-plugin-uglify": "^6.0.4"
   },
   "browserify": {
     "transform": [

rollup.config.js

@@ -0,0 +1,48 @@
+import replace from 'rollup-plugin-replace';
+import nodeResolve from 'rollup-plugin-node-resolve';
+import commonjs from 'rollup-plugin-commonjs';
+import {uglify} from 'rollup-plugin-uglify';
+import babel from 'rollup-plugin-babel';
+
+function stripEnvVariables(env) {
+  return {
+    __DEV__: env === 'production' ? 'false' : 'true',
+    'process.env.NODE_ENV': `'${env}'`,
+  };
+}
+
+export default [
+  {
+    input: 'index.js',
+    output: {
+      file: 'prop-types.js',
+      format: 'umd',
+      name: 'PropTypes'
+    },
+    plugins: [
+      babel({
+        exclude: 'node_modules/**'
+      }),
+      replace(stripEnvVariables('development')),
+      nodeResolve(),
+      commonjs()
+    ]
+  },
+  {
+    input: 'index.js',
+    output: {
+      file: 'prop-types.min.js',
+      format: 'umd',
+      name: 'PropTypes'
+    },
+    plugins: [
+      babel({
+        exclude: 'node_modules/**'
+      }),
+      replace(stripEnvVariables('production')),
+      nodeResolve(),
+      commonjs(),
+      uglify()
+    ]
+  }
+];