We will continue learning Node.js in this lesson by going into depth, covering modules essential to back-end development with Node.js. We’ll cover core Node.js modules such as events, error, buffer, fs, and timer modules. We will also learn how to get user input and output and create readable and writable streams. These topics will not only help you get a deeper understanding of Node.js but will also build on the topics that have been covered thus far.


Review the code in app.js. To see the outputs of the code, type node app.js in the terminal and press Enter or Return. When you are ready to move on, click “Next”.

Here are some things that are going on in the code:

  • The events module provides EventEmitter objects used to assign listener functions triggered on specified events.
  • The buffer module is used to handle binary data. In app.js, a Buffer object is being created and then converted to a string.
  • The fs module is used to interact with the user’s filesystem. In app.js, a statement is logged that verifies that a file was provided in a callback function.
  • The timer module provides the setImmediate() function which runs immediately after the current poll phase is completed. Take note of when 'Welcome to Node.js' is logged to the terminal.

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