Build UMD dist file with Rollup

.gitignore

 .env
 package-lock.json
+dist/
 bower_components/
 node_modules/
 sauce_connect/

Makefile

-test: node_modules/ lint
+test: lint dist/fetch.umd.js
 	./script/test
 
 lint: node_modules/
 	./node_modules/.bin/eslint --report-unused-disable-directives *.js test/*.js
 
+dist/fetch.umd.js: fetch.js rollup.config.js node_modules/
+	./node_modules/.bin/rollup -c
+
 node_modules/:
 	npm install
 

package.json

@@ -2,7 +2,8 @@
   "name": "whatwg-fetch",
   "description": "A window.fetch polyfill.",
   "version": "2.0.3",
-  "main": "fetch.js",
+  "main": "./dist/fetch.umd.js",
+  "module": "./fetch.js",
   "repository": "github/fetch",
   "license": "MIT",
   "devDependencies": {
@@ -12,13 +13,16 @@
     "mocha": "2.1.0",
     "mocha-phantomjs-core": "2.0.1",
     "promise-polyfill": "6.0.2",
+    "rollup": "^0.59.1",
     "url-search-params": "0.6.1"
   },
   "files": [
     "LICENSE",
+    "dist/fetch.umd.js",
     "fetch.js"
   ],
   "scripts": {
+    "prepublish": "make dist/fetch.umd.js",
     "test": "make"
   }
 }

rollup.config.js

+export default {
+  input: 'fetch.js',
+  output: {
+    file: 'dist/fetch.umd.js',
+    format: 'umd',
+    name: 'WHATWGFetch'
+  }
+}

test/test.html

@@ -34,7 +34,7 @@
 
   <script src="/node_modules/promise-polyfill/promise.js"></script>
   <script src="/test/test.js"></script>
-  <script src="/fetch.js"></script>
+  <script src="/dist/fetch.umd.js"></script>
 
   <script>
     var runner = mocha.run();

test/worker.js

@@ -6,7 +6,7 @@ self.assert = chai.assert
 
 importScripts('/node_modules/promise-polyfill/promise.js')
 importScripts('/test/test.js')
-importScripts('/fetch.js')
+importScripts('/dist/fetch.umd.js')
 
 function title(test) {
   return test.fullTitle().replace(/#/g, '')