10 09 babel链式配置

babel.config.js

@@ -1,5 +1,8 @@
 module.exports = {
   presets: [
     '@vue/app'
+  ],
+  plugins: [
+    "@babel/plugin-proposal-optional-chaining"
   ]
 }

package.json

@@ -44,6 +44,7 @@
   },
   "devDependencies": {
     "@babel/core": "7.0.0",
+    "@babel/plugin-proposal-optional-chaining": "^7.11.0",
     "@babel/register": "7.0.0",
     "@vue/cli-plugin-babel": "3.6.0",
     "@vue/cli-plugin-eslint": "^3.9.1",