Switch the build process to rollup.js

Makes the minified UMD build 2.4kb smaller

package.json

@@ -31,21 +31,19 @@
   },
   "scripts": {
     "test": "jest",
-    "umd": "NODE_ENV=development browserify index.js -t envify --standalone PropTypes -o prop-types.js",
-    "umd-min": "NODE_ENV=production browserify index.js -t 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": "yarn build"
   },
   "devDependencies": {
     "babel-jest": "^19.0.0",
     "babel-preset-react": "^6.24.1",
-    "browserify": "^14.3.0",
-    "bundle-collapser": "^1.2.1",
-    "envify": "^4.0.0",
     "jest": "^19.0.2",
     "react": "^15.5.1",
-    "uglifyify": "^3.0.4",
-    "uglifyjs": "^2.4.10"
+    "rollup": "^0.50.1",
+    "rollup-plugin-commonjs": "^8.3.0",
+    "rollup-plugin-node-resolve": "^3.0.2",
+    "rollup-plugin-replace": "^2.0.0",
+    "rollup-plugin-uglify": "^3.0.0"
   },
   "browserify": {
     "transform": [

rollup.config.js

@@ -0,0 +1,43 @@
+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';
+
+function createConfig(file, opts = {}) {
+  const options = Object.assign({
+    production: false,
+    uglify: false
+  }, opts);
+
+  const config = {
+    input: 'index.js',
+    output: {
+      file: file,
+      format: 'umd',
+      name: 'PropTypes'
+    },
+    plugins: [
+      replace(stripEnvVariables(options.production)),
+      nodeResolve(),
+      commonjs()
+    ]
+  };
+
+  if (options.uglify) {
+    config.plugins.push(uglify())
+  }
+
+  return config;
+}
+
+function stripEnvVariables(production) {
+  return {
+    __DEV__: production ? 'false' : 'true',
+    'process.env.NODE_ENV': production ? "'production'" : "'development'",
+  };
+}
+
+export default [
+  createConfig('prop-types.js'),
+  createConfig('prop-types.min.js', {uglify: true, production: true})
+];