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Read File Contents to Variable in NodeJS 📚

Reading and handling file operations is a common task in many web applications and scripts. Node.js, being a powerful JavaScript runtime, offers multiple ways to read files and store their contents into variables. This process can be achieved using Node.js's built-in fs (File System) module. Whether you're working on a small script or a large-scale application, knowing how to perform these operations is crucial.

Synchronous File Reading 🔄

The fs module in Node.js provides fs.readFileSync for synchronous file reading. This method is straightforward and blocks the Node.js event loop until the file reading is complete. It's simple to use but generally recommended for initial configuration loading or small files to avoid performance bottlenecks.

How to Use fs.readFileSync

const fs = require('fs');

// Specify the file path
const filePath = 'path/to/your/file.txt';

// Read the file contents synchronously
const fileContents = fs.readFileSync(filePath, 'utf8');

// Output the file contents

In this example, fs.readFileSync takes two arguments: the file path and the file encoding. The encoding 'utf8' ensures that the file content is returned as a string.

Asynchronous File Reading 🚀

For non-blocking I/O operations, Node.js offers fs.readFile, an asynchronous method to read files. This approach is more suitable for web applications as it doesn't block the event loop, allowing Node.js to handle other operations concurrently.

How to Use fs.readFile

const fs = require('fs');

// Specify the file path
const filePath = 'path/to/your/file.txt';

// Read the file contents asynchronously
fs.readFile(filePath, 'utf8', (err, data) => {
  if (err) {
  // Output the file contents

With fs.readFile, the function takes a callback as the third argument, which is called once the file reading is complete or an error occurs. The callback receives two arguments: an error object (if an error occurred) and the data read from the file.


Understanding how to read files in Node.js is fundamental for many applications. Whether you choose the synchronous or asynchronous approach depends on your application's requirements and the file size. For most web applications, the asynchronous method is preferred due to its non-blocking nature.

Remember, reading files is just the beginning. Node.js and its fs module offer a plethora of file system operations like writing to files, appending data, and much more. Exploring these capabilities can significantly enhance your Node.js applications.

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