Front-end configuration optional chain + double question mark syntactic sugar

Sample code

const highlightedColor = this.options?.infoStyle?.highlightedColor || '#FFFFFF';
const width = this.options?.width ?? 100;

1、babel.config.js

module.exports = {
    
    
	presets: [
		'@vue/app',
		'@vue/babel-preset-jsx'
	],
	plugins: [
		// 双问号
		'@babel/plugin-proposal-nullish-coalescing-operator',
		// 可选链
		'@babel/plugin-proposal-optional-chaining'
	]
};

package.json

  "devDependencies": {
    
    
    "@babel/core": "^7.0.0",
    "@babel/plugin-proposal-nullish-coalescing-operator": "^7.18.6",
    "@babel/plugin-proposal-optional-chaining": "^7.20.7",
    "@babel/register": "^7.0.0",
    "babel-eslint": "^10.1.0",
    "babel-loader": "^8.2.2",
  },