Add sample `tsconfig.json` to docs for adding TypeScript to existing project

It would be useful if the documentation for adding TypeScript included a sample tsconfig.json for people who are upgrading existing projects. Currently the documentation states that one will be generated for you, but that only applies if you are initializing a new project.

In the meantime, for those who run into this issue, I created a dummy project and ran the initialization to get this config:

{
  "compilerOptions": {
    "target": "es5",
    "lib": [
      "dom",
      "dom.iterable",
      "esnext"
    ],
    "allowJs": true,
    "skipLibCheck": true,
    "esModuleInterop": true,
    "allowSyntheticDefaultImports": true,
    "strict": true,
    "forceConsistentCasingInFileNames": true,
    "module": "esnext",
    "moduleResolution": "node",
    "resolveJsonModule": true,
    "isolatedModules": true,
    "noEmit": true,
    "jsx": "preserve"
  },
  "include": [
    "src"
  ]
}

If this is the correct “default” config, then this can be added to or linked to the existing documentation page about TypeScript to make it easier for existing projects to convert.

[johndturn]

I’ve just converted an existing, non-ejected CRA-based project from JavaScript to TypeScript, and I can confirm that the tsconfig.json file was generated for me.

For reference, I’m on react-scripts: 2.1.3

[Timer]

We have changed the template a few times. The template created when you create a project or change an existing project is identical (the new project actually calls the exact code).

If at any time you want to regenerate the file, you can just delete your tsconfig.json and re-run npm start.

Maybe we can note that?