typescript-eslint-parser-for-extra-files enables ESLint to lint TypeScript code found in non-standard locations or files not explicitly part of your main project. It extends standard TypeScript ESLint parsing by allowing you to specify and process additional files, like scripts or configuration files, that use TypeScript syntax. This is helpful for maintaining consistent code style across your entire project and preventing errors in less commonly checked files. It ensures comprehensive linting even for TypeScript code outside typical source directories.