Learn to build web applications using Node.js and the Express framework.

Become a MEAN Stack Developer

Node.js is a runtime environment that enables JavaScript to run outside the browser. In this module, we'll learn the fundamentals of Node.js to build portable applications. We'll learn about the components of Node.js and make patterns using these. We'll also explore the API to learn how to create modules and write code for unique data files. Moreover, we'll delve into the features and practices of JavaScript and build a REST API using the Express framework from scratch. Moving on, we'll use Passport.js and JSON web tokens to establish authentication tokens. We’ll then create a live trivia game with Socket.IO. By the end of this module, we'll be equipped with extensive knowledge to build rich and comprehensive Node.js applications running on the server with JavaScript.

Learn Node.js from Scratch

## Write to a file 

Let's implement a `writeFile()` function that asynchronously writes data to `test.txt`, replacing all existing data with new data passed to `writeFile()`.

We can write to a file with `fs.writeFile()`. This method accepts two arguments:

- It accepts a file path.
- It accepts data to be written to the file.

After writing to `test.txt` with the implemented function, check the contents of `test.txt` displayed by the `readFile()` function.

Let’s add the required code to the `file-system.js` file and see what happens:

# Write to a file 

Let's implement a `writeFile()` function that asynchronously writes data to `test.txt`, replacing all existing data with new data passed to `writeFile()`.

We can write to a file with `fs.writeFile()`. This method accepts two arguments:

- It accepts a file path.
- It accepts data to be written to the file.

After writing to `test.txt` with the implemented function, check the contents of `test.txt` displayed by the `readFile()` function.

Let’s add the required code to the `file-system.js` file and see what happens:

Node.js Overview

The Node.js API

JavaScript Essentials Review

Building a RESTful API with Express

Authentication with Passport.js and JSON Web Tokens

Build a Live Trivia Game with Socket.IO

Appendix

Conclusion

Coding Exercise: Write to a File

Write to a file