example tsconfig file for making type checking work with javascript project and including custom type files.

tsconfig.json

{
  "compilerOptions": {
    "allowJs": true,
    "allowSyntheticDefaultImports": true,
    "baseUrl": "./",
    "checkJs": true,
    "jsx": "react",
    "module": "ESNext",
    "moduleResolution": "classic",
    "outDir": "lib",
    "paths": {
      "*": [
        "src/@types/*",
        "node_modules/@types/*"
      ]
    },
    "target": "ESNext",
    "typeRoots": [
      "node_modules/@types"
    ]
  },
  "include": [
    "./src/**/*"
  ]
}