{
  "compilerOptions": {
    "allowSyntheticDefaultImports": true,
    "composite": true,
    "declaration": true,
    "esModuleInterop": true,
    "incremental": true,
    "jsx": "react",
    "lib": ["dom", "es2015"],
    "module": "commonjs",
    "moduleResolution": "node",
    "noEmitOnError": true,
    "noImplicitAny": true,
    "noUnusedLocals": true,
    "preserveWatchOutput": true,
    "resolveJsonModule": true,
    "target": "es2015",
    "types": []
  }
}

{
  "compilerOptions": {
    "allowSyntheticDefaultImports": true,
    "composite": true,
    "declaration": true,
    "esModuleInterop": true,
    "incremental": true,
    "jsx": "react",
    "module": "commonjs",
    "moduleResolution": "node",
    "noEmitOnError": true,
    "noImplicitAny": true,
    "noUnusedLocals": true,
    "preserveWatchOutput": true,
    "resolveJsonModule": true,
    "target": "es2017",
    "types": []
  }
}

Update Typescript target to es2017
Update Typescript target to es2017

This brings native async/await and many other features. According to http://kangax.github.io/compat-table/es2016plus/, Firefox 60 (ESR), Chrome, and Safari all support most es2017 features for a while. I don’t think we use the features that are not well supported in recent browsers.