Why Reading files with promises (fs.promises) in Node.js? - Purpose & Use Cases

The Big Idea

Discover how to make file reading in Node.js simple and clean with promises!

The Scenario

Imagine you want to read a file in Node.js and then do something with its content, like showing it on a website or processing data.

You try to read the file using the old callback method, nesting multiple functions inside each other.

The Problem

Callbacks quickly become messy and hard to follow, especially when you need to read multiple files or handle errors.

This makes your code confusing and prone to mistakes, like forgetting to handle errors or mixing up the order of operations.

The Solution

Using fs.promises lets you read files with promises, making your code cleaner and easier to read.

You can use async/await to write code that looks like normal steps, but still handles asynchronous file reading smoothly.

Before vs After

✗ Before

fs.readFile('file.txt', (err, data) => {
  if (err) throw err;
  console.log(data.toString());
});

✓ After

import { promises as fs } from 'fs';

async function readFile() {
  const data = await fs.readFile('file.txt', 'utf8');
  console.log(data);
}

readFile();

What It Enables

This approach makes it simple to write clear, step-by-step code that reads files and handles errors without deeply nested callbacks.

Real Life Example

Imagine building a website that loads user data from files. Using fs.promises, you can easily read those files one after another, showing the data smoothly without confusing code.

Key Takeaways

Callbacks for reading files can get messy and hard to manage.

fs.promises lets you use promises and async/await for cleaner code.

This makes reading files easier, clearer, and less error-prone.