Lesson 55/100

Tutorials HTML Tutorial

WebSockets — Complete Guide

WebSockets — Complete Guide: free step-by-step lesson with examples, common mistakes, and interview tips — part of HTML Tutorial on Toolliyo Academy.

On this page

HTML Tutorial · Lesson 55 of 100

WebSockets

Basics ✓Forms & semantics ✓APIs & performanceProjects

APIs & performance · 3 — HTML5, CSS/JS, security · ~10 min · HTML — HTML5 APIs & Advanced Features

What is this?

WebSockets open a persistent two-way channel between browser and server for live updates.

Why should you care?

MarkupVerse trading and chat widgets push prices without polling.

See it live — copy this example

Save as demo.html and open in your browser, or use Run Example below.

<section aria-live="polite">
  <h2>Live FX — MarkupVerse Pay</h2>
  <p>USD/INR: <strong id="rate">—</strong></p>
  <p id="ws-status">Connecting…</p>
</section>
<script>
const ws = new WebSocket('wss://echo.websocket.events');
ws.onopen = () => { document.getElementById('ws-status').textContent = 'Connected'; ws.send('USDINR'); };
ws.onmessage = e => { document.getElementById('rate').textContent = e.data || '83.42'; };
ws.onclose = () => { document.getElementById('ws-status').textContent = 'Disconnected'; };
</script>

Run Example »

Edit the code below and click Run to see the result in Toolliyo’s live editor.

Code
Result

What happened?

  • Use wss:// in production.
  • Reconnect on close.
  • Show connection state to users.

Practice next

  1. Open a WebSocket.
  2. Send a symbol on open.
  3. Update DOM on message.
  4. Add exponential backoff reconnect.
  5. Show last-updated timestamp.

Remember

Persistent socket. wss in prod. Handle reconnect.

MarkupVerse live rates

Pay page shows USD/INR tick updates.

Outcome: Rate changes without refresh.

Interview prep for this lesson

Practice these questions aloud after reading—each links to a full structured answer.

Junior Detailed
Explain JavaScript in the context of HTML.
Short answer: JavaScript runs single-threaded with an event loop. Closures capture lexical scope; promises/async handle I/O without blocking the UI thread. Real-world example (ShopNest) On the ShopNest storefront UI, thi…
Mid Detailed
What are common mistakes teams make with Components when using HTML?
Short answer: Interviewers want a crisp definition, a practical example from your projects, and awareness of trade-offs—not textbook dumps. Explain a bit more How to structure your answer (60–90 seconds) Define Component…
Senior Detailed
How would you debug a production issue related to State in a HTML application?
Short answer: Interviewers want a crisp definition, a practical example from your projects, and awareness of trade-offs—not textbook dumps. Explain a bit more How to structure your answer (60–90 seconds) Define State in…
Junior Detailed
Describe a real-world scenario where Performance mattered in a HTML project.
Short answer: Interviewers want a crisp definition, a practical example from your projects, and awareness of trade-offs—not textbook dumps. Explain a bit more How to structure your answer (60–90 seconds) Define Performan…
Questions on this lesson 0

Sign in to ask a question or upvote helpful answers.

No questions yet — be the first to ask!

HTML Tutorial
Course syllabus

HTML Tutorial

HTML — Foundations
HTML — Media & Content
HTML — Forms & Validation
HTML — Semantic HTML & SEO
HTML — Accessibility & Responsive Design
HTML — HTML5 APIs & Advanced Features
HTML — with CSS & JavaScript
HTML — Performance & Security
HTML — Testing & Deployment
HTML — Real-World Projects
Toolliyo Assistant
Ask about tutorials, ebooks, training, pricing, mentor services, and support. I use public site content only—not admin or internal tools.

care@toolliyo.com

Need callback? Share your details