JavaScript Mastery

Happy weekend, JSM Friends! 😜

#JavaScript Coding Challenge! 🔥 What’s the output of the code below - and why? ⬇️ console.log(null || 0 || "" || "Hello" || 42); ----------- ⚠️ Not sure of the answer? Try it out in your console and see if you can explain what’s happening step-by-step! (Being able to explain your code clearly is one of the most important skills of a great developer!) ------------ 💭 Think about: - How || short-circuits - Which values are truthy and falsy ---------- ‼️ For a limited time only - complete our ‘State of JSM’ survey and get 14 days FREE access to JS Mastery PRO (jsmastery.com)! You’ll get access to all of our best courses - including our Complete Path to JavaScript Mastery Course, Next 16 Course, Complete Testing Course, and more. It takes just 7 minutes 👉 https://lnkd.in/gTnnG_kQ

NEW VIDEO: WebSockets Crash Course | Build a High-Frequency Sports Broadcast Engine! 🚀 Have you ever opened a video to learn real-time apps, only to watch someone import a paid service and call it “magic”? Then, you hit an interview and get asked about handshakes, ghost connections, or why streams freeze - and everything falls apart! In 2026, anyone can use AI or pay for a service. Engineers build the service. 1️⃣ Here’s what you’ll actually learn: → How a WebSocket starts life as HTTP → What the 101 Switching Protocols response really does → How full-duplex communication lets servers push data instantly → How to keep thousands of connections stable → Why ghost connections silently kill servers → How ping-pong heartbeats keep everything alive → Broadcast vs unicast vs rooms → Pub/sub architecture for live sports and large-scale events → Back pressure, memory safety, and when WebSockets aren’t the right tool 2️⃣ Then, we go from theory to production: You’ll build a high-fidelity live sports match engine that broadcasts scores and play-by-play commentary - in under 10 milliseconds! 😱 Production stack: → React for a real-time UI that updates like a stadium scoreboard → Node.js for the event-driven core → Express for the handshake and REST APIs → Native WebSockets (ws) for protocol-level control → PostgreSQL + Drizzle ORM → Arcjet for security, rate limiting, and DDoS protection → ManageEngine Site24x7 for monitoring latency and system health → CodeRabbit for clean, scalable, production-ready code → Hostinger for deployment By the end of this course, you won’t just say, “Yeah, I can build a real-time app.” You’ll explain exactly how the data moves through the wire. If you’re serious about leveling up from watching tutorials to becoming hire-ready, this one’s for you. Get started here ➡️ https://lnkd.in/gvpVszxs

"I've just launched a portfolio that brings a fresh perspective to how I showcase my work. Instead of the traditional layout, I built an interactive experience that lets you explore my projects like browsing folders on your computer." ~ Great work, Dylan Lopez! 🔥

Let's learn how to select DOM elements to bring your website to life! 🚀 #javascript

#JavaScript Coding Challenge! 🔥 What’s the output of the code below - and why? ⬇️ const nums = [1, 2, 3, 4]; const result = nums.map(n => n * 2).reduce((acc, n) => acc + n, 0); console.log(result); ----------- ⚠️ Not sure of the answer? Try it out in your console and see if you can explain what’s happening step-by-step! (Being able to explain your code clearly is one of the most important skills of a great developer!) ------------ 💭 Think about: - What map() returns - How reduce() accumulates values - Why the initial value matters ---------- ‼️ For a limited time only - complete our ‘State of JSM’ survey and get 14 days FREE access to JS Mastery PRO (jsmastery.com)! You’ll get access to all of our best courses - including our Complete Path to JavaScript Mastery Course, Next 16 Course, Complete Testing Course, and more. It takes just 7 minutes 👉 https://lnkd.in/gTnnG_kQ

UPCOMING YOUTUBE VIDEO! 😱 Master WebSockets in this crash course, moving from core theory to building a high-frequency "Broadcast Engine." Learn how to ingest data from admin sources or APIs to deliver live match scores, commentary, and ball-by-ball updates to 100,000+ simultaneous users with sub-second latency!

Reading these comments week after week is truly motivating! ❤️ Thank you for all the support, feedback, and positive energy - it means a lot!

#JavaScript Coding Challenge! 🔥 What’s the output of the code below - and why? ⬇️ let a = 0; let b = 'JS'; const result = a && b || a + b; console.log(result); ----------- ⚠️ Not sure of the answer? Try it out in your console and see if you can explain what’s happening step-by-step! (Being able to explain your code clearly is one of the most important skills of a great developer!) ------------ 💭 Think about: - How && and || short-circuit - Operator precedence - What + does with mixed types - What values logical operators return ---------- ‼️ For a limited time only - complete our ‘State of JSM’ survey and get 14 days FREE access to JS Mastery PRO (jsmastery.com)! You’ll get access to all of our best courses - including our Complete Path to JavaScript Mastery Course, Next 16 Course, Complete Testing Course, and more. It takes just 7 minutes 👉 https://lnkd.in/gTnnG_kQ

You can ship a stunning Next.js app, but if a small change introduces a bug, your users won’t care how polished your UI looks. That’s why testing matters.