solana-with-rpc-optimizations/web3.js/babel.config.json

{
  "presets": [
    ["@babel/preset-env"],
    ["@babel/preset-flow"]
  ],
  "plugins": [
    "@babel/plugin-proposal-class-properties"
  ],
  "env": {
    "test": {
      "plugins": ["@babel/plugin-transform-runtime"],
      "presets": ["@babel/preset-flow"]
    }
  }
}