The Node.js File System (fs) Module
📌 Covered in this chapter:
Reading & Writing Files · fs/promises · Sync vs Async Methods · Directories · File Stats
Read, write, append, and manage files and directories using Node's fs module, in both promise-based and synchronous forms.
1The Node.js File System (fs) Module — What You'll Learn
Read, write, append, and manage files and directories using Node's fs module, in both promise-based and synchronous forms.
Here's everything this chapter covers, in the order you'll learn it:
- The file system module
- Reading files
- Writing files
- Appending to files
- Renaming files
- Deleting files
- Creating directories
- Reading directory contents
- Getting file statistics (size, dates)
- Understanding file paths
- Synchronous vs asynchronous methods
- Promise-based file APIs (fs/promises)
- File permissions
- Error handling for file operations
2Working Example
💻 Example: The Node.js File System (fs) Module
JavaScript
▶ Run in Compiler
import { writeFile, readFile } from "node:fs/promises";
await writeFile("notes.txt", "Learning Node.js");
const content = await readFile("notes.txt", "utf8");
console.log(content);3Best Practices & Common Pitfalls
💡 Key things to remember:
- Prefer the fs/promises API with async/await over the older callback-based fs functions for cleaner code.
- The *Sync functions (readFileSync, writeFileSync) block the event loop — only use them for one-off scripts, never inside a running server's request handlers.
❓ Frequently Asked Questions (FAQ)
Q What's the most important thing to understand about the node.js file system (fs) module?
Focus on: Reading & Writing Files · fs/promises · Sync vs Async Methods · Directories · File Stats. These are the core building blocks this chapter's examples are built around, and they show up repeatedly in later chapters of this course.
Q Do I need external npm packages for the node.js file system (fs) module?
Only where explicitly shown in the code examples above (like Express, Zod, or Socket.IO) — otherwise, this chapter relies entirely on Node.js's own built-in capabilities.