rootDir

rootDir is a term used in computing and software development to denote the root directory for a project or a particular build process. It is not a universal standard, but a convention used by many tools to specify where path resolution should begin. The exact meaning and behavior of rootDir vary by context and should be defined in the documentation of the specific tool or language.

In TypeScript, rootDir is a compiler option inside tsconfig.json. It designates the root of the input files to be compiled. When used together with outDir, it helps preserve the directory structure of the source files in the emitted JavaScript. If rootDir is not explicitly set, the compiler infers a root based on the include patterns.

Beyond TypeScript, rootDir commonly serves as the base directory for a build, packaging, or module-resolution process. In multi-root or monorepo setups, rootDir helps tools determine how to locate source files, where to place outputs, and how to resolve relative imports. Some scripts compute paths relative to rootDir to enable portable builds across environments.

Practical considerations include ensuring consistent definitions across configurations, handling absolute versus relative paths, and accounting for platform differences in path separators. When working with rootDir, it is important to keep a clear boundary between source inputs and generated outputs, and to align the root with the project’s actual top-level directory.

In summary, rootDir identifies the starting point for file resolution in a given tool or workflow. Its precise effect depends on the specific configuration and should be consulted in the relevant documentation.