babel.config.js

module.exports = {
    sourceType: "unambiguous",
    presets: [
        [
            "@babel/preset-typescript",
            {
                allowDeclareFields: true,
            },
        ],
        "@babel/preset-react",
        [
            "@babel/preset-env",
            {
                useBuiltIns: "usage",
                corejs: { version: "3.9", proposals: true },
                targets: {
                    node: "12",
                    browsers: ["> 0.2% and not dead", "firefox >= 44"],
                },
            },
        ],
    ],
    plugins: [
        [
            "@babel/plugin-transform-typescript",
            {
                allowDeclareFields: true,
            },
        ],
        "@babel/plugin-proposal-class-properties",
        "@babel/plugin-transform-runtime",
    ],
};