什么控制 create-react-app 中的 ECMAScript 版本？

Question

I am currently running a create-react-app, using react v16.2. I would like to use Optional chaining from ECMAScript 2021 (ES12). What governs the ECMAScript version in my app?

For example, in a nodejs backend app I know I need to upgrade my version of node, but I'm unsure how this translates to React.

EDIT - I'm currently on v16.2 and when i try to use optional chaining, I get an error message asking me to use a babel polyfill.

Answer 1

React uses Babel to transpile and polyfill the code ie convert your ES2015+ code to ES5 syntax. create-react-app uses Webpack as the build tool and Babel as the transpiler so you should safely be able to use the optional chaining ? syntax and when you run / build your app, it will work as intended.

Answer 2

Babel is what decides this, it's a JS-to-JS transpiler. In create-react-app, you get whatever plugins and presets the maintainers decided on, unless/until you decide to eject so you can manage your own config. If you do decide to do that, you can start with the config they provide and then add new babel presets and plugins on top of that. As of a couple years ago , there's no good way to add to their config without ejecting. For your specific need, it looks like they include that plugin , so if your dependencies are up to date, you should be good to go.