chore: Add ES module build (#370)

* chore: Add ES module build

* nit

.babelrc.js

@@ -0,0 +1,18 @@
+module.exports = (api) => ({
+  presets: [
+    [
+      '@4c',
+      {
+        targets: {},
+        modules: api.env() === 'esm' ? false : 'commonjs',
+      },
+    ],
+  ],
+  plugins: [api.env() !== 'esm' && 'add-module-exports'].filter(Boolean),
+
+  env: {
+    test: {
+      plugins: ['istanbul'],
+    },
+  },
+});

.eslintignore

@@ -1,3 +1,7 @@
+!.babelrc.js
+!.eslintrc.js
+
 **/coverage/
 **/lib/
+**/es/
 **/node_modules/

.eslintrc.js

@@ -0,0 +1,10 @@
+module.exports = {
+  extends: ['4catalyzer', 'prettier'],
+  plugins: ['prettier'],
+  env: {
+    browser: true,
+  },
+  rules: {
+    'prettier/prettier': 'error',
+  },
+};

.gitignore

@@ -1,30 +1,119 @@
 # Logs
 logs
 *.log
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+lerna-debug.log*
+
+# Diagnostic reports (https://nodejs.org/api/report.html)
+report.[0-9]*.[0-9]*.[0-9]*.[0-9]*.json
 
 # Runtime data
 pids
 *.pid
 *.seed
+*.pid.lock
 
 # Directory for instrumented libs generated by jscoverage/JSCover
 lib-cov
 
 # Coverage directory used by tools like istanbul
 coverage
+*.lcov
+
+# nyc test coverage
+.nyc_output
 
-# Grunt intermediate storage (http://gruntjs.com/creating-plugins#storing-task-files)
+# Grunt intermediate storage (https://gruntjs.com/creating-plugins#storing-task-files)
 .grunt
 
+# Bower dependency directory (https://bower.io/)
+bower_components
+
 # node-waf configuration
 .lock-wscript
 
-# Compiled binary addons (http://nodejs.org/api/addons.html)
+# Compiled binary addons (https://nodejs.org/api/addons.html)
 build/Release
 
-# Dependency directory
-# https://www.npmjs.org/doc/misc/npm-faq.html#should-i-check-my-node_modules-folder-into-git
-node_modules
+# Dependency directories
+node_modules/
+jspm_packages/
+
+# Snowpack dependency directory (https://snowpack.dev/)
+web_modules/
+
+# TypeScript cache
+*.tsbuildinfo
+
+# Optional npm cache directory
+.npm
+
+# Optional eslint cache
+.eslintcache
+
+# Microbundle cache
+.rpt2_cache/
+.rts2_cache_cjs/
+.rts2_cache_es/
+.rts2_cache_umd/
+
+# Optional REPL history
+.node_repl_history
+
+# Output of 'npm pack'
+*.tgz
+
+# Yarn Integrity file
+.yarn-integrity
+
+# dotenv environment variables file
+.env
+.env.test
+
+# parcel-bundler cache (https://parceljs.org/)
+.cache
+.parcel-cache
+
+# Next.js build output
+.next
+
+# Nuxt.js build / generate output
+.nuxt
+dist
+
+# Gatsby files
+.cache/
+# Comment in the public line in if your project uses Gatsby and not Next.js
+# https://nextjs.org/blog/next-9-1#public-directory-support
+# public
+
+# vuepress build output
+.vuepress/dist
+
+# Serverless directories
+.serverless/
+
+# FuseBox cache
+.fusebox/
+
+# DynamoDB Local files
+.dynamodb/
+
+# TernJS port file
+.tern-port
+
+# Stores VSCode versions used for testing VSCode extensions
+.vscode-test
+
+# yarn v2
+
+.yarn/cache
+.yarn/unplugged
+.yarn/build-state.yml
+.pnp.*
 
-# Transpiled code
+# Transpiled code.
 /lib
+/es

package.json

@@ -3,12 +3,17 @@
   "version": "0.10.0",
   "description": "Pluggable browser scroll management",
   "files": [
-    "lib"
+    "lib",
+    "es"
   ],
   "main": "lib/index.js",
+  "module": "es/index.js",
   "types": "lib/index.d.ts",
   "scripts": {
-    "build": "babel src -d lib --delete-dir-on-start && cpy types/*.d.ts lib",
+    "build": "npm run build:cjs && npm run build:esm && npm run build:types",
+    "build:cjs": "babel -d lib --delete-dir-on-start src",
+    "build:esm": "babel --env-name esm -d es --delete-dir-on-start src",
+    "build:types": "cpy types/*.d.ts lib",
     "format": "eslint --fix . && npm run prettier -- --write",
     "lint": "eslint . && npm run prettier -- -l",
     "prepublish": "npm run build",

test/.eslintrc.js

@@ -0,0 +1,16 @@
+module.exports = {
+  env: {
+    mocha: true,
+  },
+  globals: {
+    expect: false,
+  },
+  rules: {
+    'import/no-extraneous-dependencies': [
+      'error',
+      {
+        devDependencies: true,
+      },
+    ],
+  },
+};