Add ES modules build

.gitignore

@@ -1 +1,7 @@
+es
+node_modules
 umd
+/*.js
+!karma.conf.js
+!tests.webpack.js
+!webpack.config.js

modules/.babelrc

@@ -1,6 +1,6 @@
 {
   "presets": [
-    [ "es2015", { "loose": true } ],
+    "../tools/es2015-preset",
     "stage-1"
   ],
   "plugins": [

package.json

@@ -7,14 +7,11 @@
   "license": "MIT",
   "scripts": {
     "start": "webpack-dev-server -d --content-base ./ --history-api-fallback --inline modules/index.js",
-    "build-lib": "babel ./modules -d . --ignore '__tests__'",
-    "build-umd": "webpack modules/index.js umd/history.js",
-    "build-min": "webpack -p modules/index.js umd/history.min.js",
-    "build": "node ./scripts/build.js",
-    "release": "node ./scripts/release.js",
-    "prepublish": "node ./scripts/build.js",
-    "test": "npm run lint && karma start",
-    "lint": "eslint modules"
+    "build": "node ./tools/build.js",
+    "prepublish": "node ./tools/build.js",
+    "release": "node ./tools/release.js",
+    "lint": "eslint modules",
+    "test": "karma start --single-run"
   },
   "dependencies": {
     "invariant": "^2.2.1",

tools/build.js

@@ -0,0 +1,44 @@
+const fs = require('fs')
+const execSync = require('child_process').execSync
+const inInstall = require('in-publish').inInstall
+const prettyBytes = require('pretty-bytes')
+const gzipSize = require('gzip-size')
+
+if (inInstall())
+  process.exit(0)
+
+const exec = (command, extraEnv) =>
+  execSync(command, {
+    stdio: 'inherit',
+    env: Object.assign({}, process.env, extraEnv)
+  })
+
+console.log('Building CommonJS modules ...')
+
+exec('babel modules -d . --ignore __tests__', {
+  BABEL_ENV: 'cjs'
+})
+
+console.log('\nBuilding ES modules ...')
+
+exec('babel modules -d es --ignore __tests__', {
+  BABEL_ENV: 'es'
+})
+
+console.log('\nBuilding history.js ...')
+
+exec('webpack modules/index.js umd/history.js', {
+  NODE_ENV: 'production'
+})
+
+console.log('\nBuilding history.min.js ...')
+
+exec('webpack -p modules/index.js umd/history.min.js', {
+  NODE_ENV: 'production'
+})
+
+const size = gzipSize.sync(
+  fs.readFileSync('umd/history.min.js')
+)
+
+console.log('\ngzipped, the UMD build is %s', prettyBytes(size))

tools/es2015-preset.js

@@ -0,0 +1,12 @@
+const buildPreset = require('babel-preset-es2015').buildPreset
+
+const BABEL_ENV = process.env.BABEL_ENV
+
+module.exports = {
+  presets: [
+    [ buildPreset, {
+      loose: true,
+      modules: BABEL_ENV === 'es' ? false : 'commonjs'
+    } ]
+  ]
+}