Understanding Isolated Modules in TypeScript

The isolatedModules enables single file transpilation, which allows tools other than TypeScript to transpile your code. It also indicates that you’re operating in a module-based system.

Setting isolatedModules to true in your tsconfig is a good practice because it improves code portability between different systems and prevents unexpected behaviors, such as the one seen with declare.

tsconfig.json

{
  "compilerOptions": {
    ...
    "isolatedModules": true
  }
}