What background knowledge is necessary to enroll in the course?

You should have a basic understanding of JavaScript, HTML, and CSS, as well as familiarity with Node.js and npm. Some prior knowledge of HTTP and web application architecture will help you grasp the server-client interactions more easily.

Who is this course for?

This course is designed for web developers and software engineers who want to learn real-time communication and file transfer in web applications. It is also suitable for those who want to explore advanced browser APIs like FileReader and Streams to handle data efficiently.

Can I preview a course before enrolling?

Yes, you can preview the first video and view the syllabus before you enroll. You must purchase the course to access content not included in the preview.

When will I have access to the lectures and assignments?

If you decide to enroll in the course before the session start date, you will have access to all of the lecture videos and readings for the course. You’ll be able to submit assignments once the session starts.

What will I get when I enroll?

Once you enroll and your session begins, you will have access to all videos and other resources, including reading items and the course discussion forum. You’ll be able to view and submit practice assessments, and complete required graded assignments to earn a grade and a Course Certificate.

When will I receive my Course Certificate?

If you complete the course successfully, your electronic Course Certificate will be added to your Accomplishments page - from there, you can print your Course Certificate or add it to your LinkedIn profile.

Why can’t I audit this course?

This course is currently available only to learners who have paid or received financial aid, when available.

Is financial aid available?

Yes. In select learning programs, you can apply for financial aid or a scholarship if you can’t afford the enrollment fee. If fin aid or scholarship is available for your learning program selection, you’ll find a link to apply on the description page.

Build an App That Uses WebSockets in 2026 to Transfer Files

Build an App That Uses WebSockets in 2026 to Transfer Files

Instructor: Packt - Course Instructors

Included with Learn more

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5 modules

Gain insight into a topic and learn the fundamentals.

Intermediate level

Recommended experience

7 hours to complete

Flexible schedule

Learn at your own pace

5 modules

Gain insight into a topic and learn the fundamentals.

Intermediate level

Recommended experience

7 hours to complete

Flexible schedule

Learn at your own pace

What you'll learn

Implement real-time WebSocket connections for seamless data communication between client and server.
Read, send, and manage large files efficiently using the FileReader and Streams APIs.
Handle user connections, broadcast messages, and monitor server-client interactions effectively.
Apply flow control, error handling, and memory management strategies for reliable web apps.

Skills you'll gain

Tools you'll learn

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There are 5 modules in this course

This course features Coursera Coach!

A smarter way to learn with interactive, real-time conversations that help you test your knowledge, challenge assumptions, and deepen your understanding as you progress through the course. Dive into the world of real-time web communication and learn how to build a fully functional WebSocket-based file transfer application. You’ll explore how data travels over the network, why metadata matters, and how WebSockets enable efficient, instant communication between clients and servers. This course equips you with practical skills to implement seamless file transfers in modern web applications. Starting from the foundational setup, you’ll learn to configure Node.js and Express servers, initiate WebSocket connections, and handle ping/pong mechanisms to maintain live communication. Step-by-step tutorials guide you through managing users, broadcasting messages, and monitoring real-time traffic, giving you a solid understanding of WebSocket workflows. The course then advances into handling actual file transfers using the FileReader API and Streams API. You’ll learn to read files in chunks, manage memory efficiently, handle errors, and create download links dynamically. Practical examples cover security considerations, flow control, and monitoring buffered data, ensuring robust and scalable file transfer solutions. This course is ideal for web developers, software engineers, and IT professionals who want to implement real-time applications. Basic familiarity with JavaScript, HTML, and Node.js is recommended. It is designed for learners at an intermediate level seeking to deepen their networking and real-time programming skills. By the end of the course, you will be able to set up WebSocket servers, manage client connections, implement chunked file transfers, monitor memory usage, and create reliable, secure, real-time file-sharing applications using modern JavaScript APIs.

In this module, we will introduce the fundamentals of sending files over a network using WebSockets. You will explore why metadata is critical for accurate communication and data integrity. Additionally, we will outline the course goals and highlight the advantages of real-time file transfer with WebSockets.

What's included

3 videos1 reading

In this module, we will guide you through setting up your development environment with Node.js and Express. You will learn how to establish WebSocket connections, implement ping/pong checks, and handle messages efficiently. The module also covers organizing your project, managing users, and updating the UI dynamically for a seamless experience.

What's included

18 videos1 assignment

18 videosTotal 97 minutes

HTML and CSS Overview8 minutes
Installing Node and Setting Up the npm Project5 minutes
Spin Up a Node HTTP Server Using Express6 minutes
Setting Up a WebSocket Server5 minutes
Writing Logic for a Simple Ping/Pong6 minutes
Initiating a WebSocket Connection From the Client With the Browser WebSocket API5 minutes
Ping and Pong Explained and Seen With Wireshark5 minutes
Setting Up a Modules Folder and Creating a uiUtils.js File8 minutes
Sending the Username Value as a String to the WebSocket Server2 minutes
Preventing the Default Refresh and Testing Our Code4 minutes
Listening for the "Message" Event on the WebSocket Server Using Switch7 minutes
Introduction to Using Map to Store Connections5 minutes
Checking Whether the Username Exists and Sending a Success or Failure Response4 minutes
Setting Up a "Message" Event Handler on the Client7 minutes
Server Broadcasting an Array of Users to All Connected Clients7 minutes
Dynamically Adding Users to the Dropdown Menu7 minutes
Removing Disconnected Users From Our Map and Updating the Element4 minutes
Final Testing and Updating UI2 minutes

1 assignmentTotal 15 minutes

Project Setup, HTTP Setup, and WebSocket Server Setup With Node.js - Assessment15 minutes

In this module, we will explore the FileReader API for reading and sending files via WebSockets. You will learn to read files in chunks, monitor transfer progress, and relay data efficiently to the receiver. The module also covers memory management, creating download links, and enabling users to abort transfers safely.

What's included

34 videos1 assignment

34 videosTotal 170 minutes

Enable the File Input Element5 minutes
Introduction to File Security4 minutes
Extracting the File That the User Has Uploaded9 minutes
Enabling the File Send Button and Defining a Click Event Listener5 minutes
Sending the File Metadata to the WebSocket Server4 minutes
Relaying the Metadata From the Server to the Receiver7 minutes
Receiving the File Metadata on the Client (by the Receiver)5 minutes
Using the FileReader API3 minutes
How Does the FileReader API Work?3 minutes
Setting Up the Initial Values for the HTML Element3 minutes
Viewing the File Read Operation in the Console and the ProgressEvent Object6 minutes
Browsers Have Limits on Chunk Sizes5 minutes
How to Create On-Demand Dummy Files in the Command Prompt2 minutes
Using the slice() Method to Read a Chunk of a File5 minutes
Defining the Size of Each Chunk to Read8 minutes
Reading One Chunk and Sending One Chunk8 minutes
Reading the Entire File With the FileReader and Testing Our Code2 minutes
Dealing With the Server Error of Chunks Exceeding Maximum Size Limit6 minutes
Stopping the FileReader When the Underlying WebSocket Connection Is Closed2 minutes
Viewing the BufferedAmount Property to Monitor Flow Control4 minutes
Why Are We Having to Look at the BufferedAmount Property?3 minutes
Using a While Loop to Monitor the BufferedAmount Value4 minutes
Implementing setTimeout and Promises to Our While() Loop (Advanced)7 minutes
Testing Code and Next Steps4 minutes
Relaying File Chunks From the Server to the Client5 minutes
Defining a Receiver Function and Changing the binaryType Property6 minutes
Updating the HTML Element and Creating an Array to Store File Chunks5 minutes
Using the URL.createObjectURL() Method to Create a Download Link for the File9 minutes
Testing Our Code4 minutes
Viewing the JS Memory Heap in Real Time6 minutes
Understanding Memory Usage and URL Blob Storage (Advanced Lecture)9 minutes
Revoking the Blob URL After Download7 minutes
Allowing the User to Abort a File Send6 minutes
Testing Our Code2 minutes

1 assignmentTotal 15 minutes

Using the FileReader API to Send Files - Assessment15 minutes

In this module, we will introduce the Streams API as an advanced method for sending files. You will implement a step-by-step streaming approach to transmit file chunks efficiently. The module concludes with testing the implementation and applying final UI improvements for a smooth file-sending experience.

What's included

6 videos1 assignment

6 videosTotal 28 minutes

What Is the Streams API?6 minutes
Implementing the 3-Step Process for Reading a File Using the Streams API8 minutes
Implementing Checks and Breaking Out of the While Loop on Read Completion5 minutes
Using the "Value" Property to Send Chunks of File Data to Our WebSocket Server3 minutes
Testing Our Code and Viewing the Chunk Sizes Returned by the Streams API3 minutes
Final UI Tweak for the Sender3 minutes

1 assignmentTotal 15 minutes

Using the Streams API to Send Files - Assessment15 minutes

In this module, we will conclude the course by reviewing the essential techniques and concepts covered. You will gain a clear understanding of how to implement WebSocket-based file transfer in your own projects. We also provide guidance on next steps and applying these skills to build robust real-time applications.

What's included

1 video2 assignments

Instructor

Packt - Course Instructors

Packt

2,044 Courses613,223 learners

Offered by

Packt

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Frequently asked questions

WebSockets is a protocol that enables two-way, real-time communication between a client and a server over a single TCP connection. It is highly relevant for modern web applications that require instant data exchange, such as chat apps, live notifications, and file transfer systems, because it reduces latency and overhead compared to traditional HTTP requests.

This course teaches you how to build a web application that can transfer files in real time using WebSockets. You will learn how to set up a Node.js server, handle client-server communication, manage file metadata, read and send files using the FileReader and Streams APIs, and implement a functional user interface for sending and receiving files efficiently.

After completing this course, you will be able to create a fully functional file transfer application that uses WebSockets for real-time communication. You will understand how to handle file metadata, send large files in chunks, manage WebSocket connections, and provide a responsive and reliable user interface for both senders and receivers.