In this Node.js tutorial for 2025, you will learn how to check a file’s size before reading it using the built-in fs module. Checking file size is a critical step in file handling to avoid memory issues, optimize performance, and prevent unnecessary read operations. This is especially important when dealing with large files, server-side uploads, log processing, or streaming operations where efficiency matters.

Node.js provides methods like fs.stat and fs.statSync that allow you to retrieve detailed information about a file, including its size in bytes. By checking a file’s size before reading it, you can decide whether to process it entirely in memory, stream it in chunks, or reject it based on size limits. This helps keep your applications fast, secure, and resource-efficient.

What You Will Learn in This Tutorial

Why checking file size before reading is important in Node.js

How to use fs.stat to get file metadata including size

Synchronous vs asynchronous approaches for checking file size

Handling errors when the file does not exist or is inaccessible

Using file size checks for conditional logic in file processing

Setting maximum allowed file sizes for security and performance

How file size checks integrate with streaming and buffering strategies

Real-World Use Cases

Preventing large file uploads from overwhelming server memory

Logging file size information before reading for analytics

Skipping empty files in batch processing systems

Validating file sizes in content management systems

Preparing pagination or chunk processing for massive datasets

Best Practices You Will Learn

Always handle errors gracefully when checking file size

Use asynchronous methods in production for better performance

Implement size limits to protect against malicious or oversized files

Combine size checks with file type validation for improved security

Log size information for troubleshooting and auditing purposes

By the end of this tutorial, you will know exactly how to check file size before reading in Node.js using efficient, reliable methods. You will understand when to use synchronous checks for simple scripts and when to adopt asynchronous checks for high-performance production systems. You will also see how this practice fits into larger file-handling workflows, such as reading, writing, moving, and deleting files.

This tutorial is part of the Node.js 2025 Playlist, which covers the full range of file system operations: creating, reading, writing, appending, renaming, moving, deleting, setting permissions, and optimizing file access. Mastering file size checks will make your applications more robust, secure, and resource-efficient.

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