.babelrc-npm.json

{
  "plugins": [
    "@babel/plugin-transform-typescript",
    "./resources/inline-invariant"
  ],
  "env": {
    "cjs": {
      "presets": [
        [
          "@babel/preset-env",
          { "modules": "commonjs", "targets": { "node": "12" } }
        ]
      ],
      "plugins": [
        ["./resources/add-extension-to-import-paths", { "extension": "js" }]
      ]
    },
    "mjs": {
      "presets": [
        ["@babel/preset-env", { "modules": false, "targets": { "node": "12" } }]
      ],
      "plugins": [
        ["./resources/add-extension-to-import-paths", { "extension": "mjs" }]
      ]
    }
  }
}