How does 'Module Detection' work in modern TypeScript?

Determines if a file is a 'script' (global scope) or a 'module' (local scope) based on imports/exports or tsconfig settings.

By default, TypeScript treats files without import or export statements as scripts, meaning their variables are in the global scope. This can cause 'Duplicate identifier' errors across files. Modern TypeScript (5.0+) provides the moduleDetection setting. Setting it to 'force' ensures every file is treated as a module, even if it lacks imports, preventing accidental global namespace pollution and aligning with ESM standards.