Chokidar and fast-glob serve fundamentally different purposes in the JavaScript toolchain ecosystem. Chokidar is a battle-tested file-watching library that monitors the file system for real-time changes—crucial for hot-reload servers, build tools, and any application needing live change detection. Fast-glob, conversely, is a high-performance globbing utility designed to scan directories and match files against patterns in a single pass or batch operation, excelling at static analysis and initial file discovery tasks.
This comparison matters because developers often conflate watching and globbing, sometimes choosing the wrong tool or misunderstanding their complementary roles. Build tool authors need chokidar's persistent monitoring capabilities, while bundler developers require fast-glob's speed when scanning large codebases. Understanding when each excels—and when to use both together—prevents performance bottlenecks and architectural mistakes in modern JavaScript tooling.
Choose chokidar when you need continuous, real-time awareness of file system changes. It's the correct choice for dev servers, live-reload systems, file synchronization tools, and any application where reacting to modifications as they happen is the core requirement. Its cross-platform reliability, minimal resource consumption, and battle-tested handling of edge cases make it the industry standard for watching. If your workflow involves 'do X whenever files change,' chokidar is your tool. Note that as of version 4, you'll need to pair it with an external globbing solution if you want pattern-based watching.
Choose fast-glob when you need to find files matching patterns once or in controlled batches. It's ideal for build tool initialization (scanning source files before bundling), static analysis tools, file cleanup scripts, or any scenario where you're asking 'what files exist right now that match these patterns?' Its performance advantage grows with directory size and pattern complexity. For tooling that needs both capabilities—like a dev server that globs files on startup then watches them—use fast-glob for the initial scan and hand the results to chokidar for monitoring. They're complementary, not competing solutions.