React's Virtual DOM optimizes UI updates

Ever wondered why changing one small thing in React doesn’t re-render the entire UI? 🤔 That’s reconciliation. In React, every update creates a new virtual DOM. But instead of updating everything, React compares the new tree with the previous one - and updates only what changed. Sounds simple, but small mistakes can break performance. 😬 • Missing or unstable keys ➡️ unnecessary re-renders • Recreating objects/functions ➡️ diffing becomes expensive • Large component trees ➡️ slower updates React is fast. But only if we help it. Reconciliation is not magic - it’s an optimization strategy based on assumptions. Understanding it changes how you structure components. 😉 Have you ever fixed a performance issue just by adding proper keys or memoization? #reactjs #frontend #webperformance #javascript #learninginpublic

React has a really elegant pattern that many developers don’t take advantage of. Instead of controlling components with dozens of props, React allows you to compose components using smaller building blocks. This pattern is often called compound components. The idea is simple: instead of configuring a component through many props, the parent component exposes smaller components that you can combine however you want. It actually took me some time working with React to realize this pattern existed, so this post is mostly for those who are earlier in their journey. If you didn’t know about this concept, you’ve probably already seen it in component libraries like Material UI, Radix UI, etc... It’s a simple idea, but it makes components much more flexible and easier to scale. Here’s a small example. #React #JavaScript #Frontend #WebDevelopment #SoftwareEngineering

"Mastering React starts with its core building blocks: Components, Props, State, and Hooks (especially useState). Components are the reusable pieces of your UI, passing data down via props (read-only) while managing dynamic behavior through state. With the introduction of Hooks in React 16.8, useState revolutionized how we handle local state in functional components — no more class boilerplate! A quick reminder: Props → Data flow from parent to child (immutable from child's perspective) useState → [value, setValue] = useState(initialValue) — triggers re-renders on updates #ReactJS #JavaScript #FrontendDevelopment #WebDevelopment #ReactHooks"

How React Remembers State Between Renders? When a component re-renders, the function runs again from top to bottom. So how does useState not reset every time? 🤔 function Counter() { const [count, setCount] = React.useState(0); return <button onClick={() => setCount(count + 1)}>{count}</button>; } Every render: The function runs again and Variables are recreated. So why doesn’t count go back to 0? What Actually Happens Internally React stores state outside the component function. Behind the scenes: 1) Each component has a Fiber node 2) React keeps a linked list of Hooks 3) It tracks Hooks based on call order State is not stored in your function. It’s stored in React’s internal Fiber system. The function is just a way for React to describe UI. Understanding this makes Hooks feel much less magical. #ReactJS #ReactInternals #ReactHooks #FrontendDevelopment #SoftwareEngineering #JavaScript

I often see developers wrap components with React.memo expecting magic improvements. But memoization only works when props are stable. If you pass a new object, array, or function on every render, React sees a new reference and re-renders anyway. Example in the screenshot below The real fix is not “wrap everything with memo”. It’s: • Stable references • Controlled state boundaries • Smaller components • Clean architecture Performance problems usually start with structure, not React itself. Optimize intentionally. Not blindly. #ReactJS #FrontendDevelopment #JavaScript #WebPerformance #SoftwareEngineering #CleanCode #FullStackDeveloper

𝗠𝗼𝘀𝘁 𝗥𝗲𝗮𝗰𝘁 𝗗𝗲𝘃𝗲𝗹𝗼𝗽𝗲𝗿𝘀 𝗢𝘃𝗲𝗿𝘂𝘀𝗲 𝘂𝘀𝗲𝗦𝘁𝗮𝘁𝗲 Not everything in React needs to be state. But many developers still store everything in useState. That leads to: • Unnecessary re-renders • Extra complexity • Harder-to-maintain components Here’s a simple way to think about it: 👉 If it affects the UI → use state 👉 If it doesn’t → use useRef useRef lets you store values across renders without triggering a re-render. This makes it perfect for things like: • Storing timers • Tracking previous values • Accessing DOM elements • Keeping mutable values Using state where a ref is enough is a common mistake. And over time, it impacts performance and code clarity. 👇 Simple comparison below Day 20/100 — sharing practical frontend engineering lessons. Do you usually default to state or think before choosing? #ReactJS #FrontendEngineering #JavaScript #WebDevelopment #SoftwareEngineering

useState vs useRef in React | Best Practices for Better Performance useState → Used to store state that updates the UI and causes component re-render. useRef → Used to store mutable values that persist between renders without causing re-render. useState is best when the value change should reflect on the screen. useRef is best when you need to keep a value without affecting rendering, such as DOM access, timers, or previous values. Using useState everywhere can cause unnecessary re-renders, while using useRef correctly helps improve performance in large React applications. Rule: If UI changes → useState If UI does not change → useRef #ReactJS #JavaScript #FrontendDevelopment #ReactHooks #MERNStack #SoftwareEngineering #WebDevelopment

Misunderstanding how JavaScript handles functions can hurt your UI performance. In JavaScript, functions are compared by reference. And in React, every render creates new function instances. So even if a function looks exactly the same, it’s actually a different reference in memory. That means when you pass a function as a prop, React sees it as a new value on every render. And if that component is wrapped with React.memo, it will still re-render. Not because React.memo doesn’t work, but because the prop actually changed. This can be solved by keeping the same function reference between renders, which is exactly what useCallback helps you do. This doesn’t mean you should use useCallback everywhere. It only matters when you need a stable function reference, like when passing props to memoized components. I’ve been using these techniques for a while, but it took me some time to really understand why they are often used together. This is a good example of how understanding the fundamentals of JavaScript can directly impact performance and behavior in React applications. (Simplified example in the image) #React #JavaScript #Frontend #WebDevelopment #SoftwareEngineering

21 Days 21 web dev procject Day 6 of Building in Public 🚀 live demo : https://lnkd.in/gYuw98q9 Today I focused on improving the UI and fixing issues in my React project. Worked on component structure, responsive layout, and debugging some annoying build errors. Things I learned today: • Proper component separation makes debugging easier • Small UI fixes can dramatically improve user experience • Build errors usually come from simple mistakes (wrong imports, wrong paths) Slow progress is still progress. #buildinpublic #webdevelopment #reactjs #javascript #100daysofcode

Why can’t we create a state variable outside the component function? const [count, setCount] = React.useState(0); ❌ function Counter() { return <div>{count}</div>; } function Counter() { const [count, setCount] = React.useState(0); ✅ return <div>{count}</div>; } Why? Because Hooks rely on the component’s render cycle. When React renders a component, it: 1️⃣ Calls the component function 2️⃣ Tracks the order of Hooks 3️⃣ Stores state internally based on that order Hooks are tightly connected to the component’s lifecycle. If you declare state outside: ❌ There is no render context ❌ No component lifecycle ❌ React can’t track it #ReactJS #ReactHooks #ReactInternals #FrontendDevelopment #JavaScript #SoftwareEngineering #WebDevelopment #LearningInPublic #ReactInterview #FrontendEngineer #TechInterview