Optional-Chaining在create-react-app中不起作用

Question

在create-react-app项目中，我在`.babelrc中使用@babel/plugin-proposal-optional-chaining

但是，我遇到此错误：Module parse failed: Unexpected token (22:16) You may need an appropriate loader to handle this file type.

这是我所有的babel依赖项：

{
  "dependencies": {
    "@babel/core": "^7.9.0",
    "@babel/node": "^7.8.7",
    "@babel/plugin-external-helpers": "^7.8.3",
    "@babel/plugin-proposal-class-properties": "^7.8.3",
    "@babel/plugin-proposal-decorators": "^7.8.3",
    "@babel/plugin-proposal-json-strings": "^7.8.3",
    "@babel/plugin-proposal-object-rest-spread": "^7.9.5",
    "@babel/plugin-proposal-optional-chaining": "^7.9.0",
    "@babel/plugin-syntax-dynamic-import": "^7.8.3",
    "@babel/plugin-syntax-import-meta": "^7.8.3",
    "@babel/plugin-transform-async-to-generator": "^7.8.3",
    "@babel/plugin-transform-modules-commonjs": "^7.9.0",
    "@babel/plugin-transform-react-constant-elements": "^7.9.0",
    "@babel/plugin-transform-react-inline-elements": "^7.9.0",
    "@babel/plugin-transform-runtime": "^7.9.0",
    "@babel/polyfill": "^7.8.7",
    "babel-plugin-add-module-exports": "^1.0.2",
    "babel-plugin-array-includes": "^2.0.3",
    "babel-plugin-inline-react-svg": "^1.1.1"
  }
}

• 节点v14.0.0
• npm 6.14.4
• 反应脚本2.1.8

我还需要什么才能使它正常工作？

Answer 1

const obj = { a: `Hello` };

// Hello World
const App = () => {
  return (
    <>
      {obj?.a}
      {obj?.b ?? ` World`}
    </>
  );
};