Checking file existence is essential for preventing errors, validating inputs, and implementing conditional file operations in Node.js applications and scripts. As the creator of CoreUI, a widely used open-source UI library, I’ve implemented file existence checks in numerous Node.js build tools, deployment scripts, and file processing utilities for CoreUI projects. From my expertise, the most modern approach is to use fs.promises.access() for asynchronous operations. This method provides proper error handling, non-blocking behavior, and integrates well with async/await patterns for clean, maintainable code.