Explain 'Isolated Modules' and transpiler compatibility.

It ensures files can be safely transpiled by tools like Babel or esbuild that operate on one file at a time.

Babel doesn't perform type-checking. Certain TS features (like const enums) require cross-file knowledge. 'isolatedModules' forces you to write code that doesn't rely on such features, ensuring compatibility with fast transpilers[cite: 1].