Reading files with promises (fs.promises) in Node.js - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is fs.promises in Node.js?

fs.promises is a part of Node.js that provides file system methods which return promises. This lets you use async/await or .then() for easier asynchronous file operations.

beginner

How do you read a file using fs.promises with async/await?

You use await fs.promises.readFile(path, options) inside an async function. It returns the file content as a buffer or string if encoding is set.

intermediate

Why is using promises better than callbacks for reading files?

Promises make code easier to read and write by avoiding nested callbacks. They allow chaining and use of async/await, which looks like normal synchronous code but runs asynchronously.

intermediate

What happens if the file does not exist when using fs.promises.readFile?

The promise is rejected with an error. You can catch this error using try/catch with async/await or .catch() when using promises.

beginner

Show a simple example of reading a text file with fs.promises and logging its content.

<pre>import { promises as fs } from 'fs';

async function readText() {
  try {
    const data = await fs.readFile('file.txt', 'utf8');
    console.log(data);
  } catch (err) {
    console.error('Error reading file:', err);
  }
}

readText();</pre>

Which method from fs.promises reads a file asynchronously?

A readFile

B readFileSync

C open

D writeFile

readFile is the asynchronous method that returns a promise to read file contents.

What does fs.promises.readFile return when successful?

A A callback function

B File descriptor number

C Undefined

D A promise that resolves to file content

It returns a promise that resolves with the file content as a buffer or string.

How do you handle errors when using async/await with fs.promises.readFile?

A Using if/else

B Using try/catch block

C Using switch statement

D No error handling needed

Errors from promises can be caught using try/catch when using async/await.

Which import syntax correctly imports fs.promises in ES modules?

A import fs from 'fs/promises';

B const fs = require('fs').promises;

C import { promises as fs } from 'fs';

D import fs from 'fs';

In ES modules, import { promises as fs } from 'fs'; imports the promises API.

What encoding option should you pass to readFile to get a string instead of a buffer?

A 'utf8'

B 'ascii'

C 'base64'

D No option needed

Passing 'utf8' returns the file content as a string.

Explain how to read a file asynchronously using fs.promises and handle errors.

Think about using async/await and try/catch blocks.

Describe the benefits of using promises over callbacks when reading files in Node.js.

Focus on code readability and error management.