build: build esm output for tree shaking

Author: elevatebart

package.json

@@ -14,7 +14,6 @@
   "dependencies": {
     "acorn": "^6.1.1",
     "buble": "^0.19.7",
-    "core-js": "^2.6.5",
     "lodash.debounce": "^4.0.8",
     "prismjs": "^1.16.0",
     "rewrite-imports": "^2.0.3",
@@ -97,7 +96,8 @@
     "dist"
   ],
   "license": "MIT",
-  "main": "./dist/vue-live.common.js",
+  "main": "dist/vue-live.common.js",
+  "module": "dist/vue-live.esm.js",
   "repository": {
     "type": "git",
     "url": "git+https://github.com/vue-styleguidist/vue-live.git"

rollup.config.js

@@ -10,10 +10,16 @@ const resolve = _path => path.resolve(__dirname, _path);
 
 export default {
   input: resolve("./src/main.js"),
-  output: {
-    file: resolve(`./dist/vue-live.common.js`),
-    format: "cjs"
-  },
+  output: [
+    {
+      file: resolve(`./dist/vue-live.common.js`),
+      format: "cjs"
+    },
+    {
+      file: resolve(`./dist/vue-live.esm.js`),
+      format: "esm"
+    }
+  ],
   plugins: [
     cjs(),
     node(),