React State Management Mistakes in Codebases

I made React slower trying to optimize it. Wrapped everything in useMemo. Added useCallback everywhere. Felt productive. Performance got worse. Here's what I didn't understand about re-renders 👇 4 things that trigger a re-render: > State change > Prop change > Parent re-renders (even if YOUR props didn't change) > Context update That third one is responsible of unnecessary re-renders I've seen in real codebases. The fix isn't memorizing APIs. It's this order: 1. Profile first Open React DevTools Profiler. Find the actual problem. Takes 2 minutes. 2. Wrap the right components in React.memo Not all of them. Only components that are expensive AND receive stable props. 3. Stabilise your functions with useCallback Without it - new function reference every render --> child always re-renders. Doesn't matter if you have React.memo. 4. useMemo for heavy calculations only Not for "this array map looks expensive." Only when Profiler proves it. The rule I follow now: Don't optimise what you haven't measured. One change in the right place beats 10 changes in the wrong ones. What's the most unnecessary useMemo you've ever written? 😄 #React #JavaScript #Frontend #WebDev

React isn’t just a library—it’s a mindset. From breaking down complex UIs into reusable components to managing state with precision, React teaches you how to think in systems, not just screens. What looks like simple code on the surface is actually layers of logic, structure, and scalability working together behind the scenes. Just like any powerful tool, the real value of React isn’t in writing code—it’s in how you architect experiences. Build components. Think in flows. Design for scale. #ReactJS #FrontendDevelopment #WebDevelopment #JavaScript #SoftwareEngineering

🚀 Mastering React Hooks – A Game Changer for Modern Development React Hooks completely changed the way we build components. No more complex class components — everything is cleaner, more readable, and reusable. Here are some of the most powerful hooks I use daily: 🔹 useState – Manage state easily 🔹 useEffect – Handle side effects like API calls 🔹 useContext – Share data across components 🔹 useReducer – Better state management for complex logic 🔹 useRef – Access DOM elements directly 🔹 useMemo & useCallback – Optimize performance 💡 Hooks not only simplify your code but also improve scalability and maintainability. If you're working with React and still not fully using Hooks, you're missing out on a huge productivity boost! 👉 What’s your favorite React Hook and why? #ReactJS #WebDevelopment #Frontend #JavaScript #ReactHooks #SoftwareDevelopment #Coding

Mastering useState: The Most Important Hook in React If you're working with React, useState is one of the first hooks you learn — and also one you’ll use in almost every component you build. Yet many developers still use it incorrectly and run into stale state or unnecessary re-renders. useState allows you to add state to functional components. It returns an array with two values: the current state and a setter function. const [count, setCount] = useState(0); The real power (and common pitfall) comes when your new state depends on the previous state. Correct way: Using the functional updater (prev) => guarantees you always get the latest state, even when multiple updates happen quickly. A few best practices I always follow: Never mutate state directly. Always create a new object/array using the spread operator (...prev). Use computed property names [dynamicKey] when your key comes from a variable. Keep state as simple as possible. If your state object gets too complex, consider useReducer. I’ve seen many bugs disappear simply by switching from setState(newValue) to the functional form when the update relies on previous values. Whether you’re building a small UI or a complex audio/video player like the one I was recently working on, mastering useState patterns makes your code more predictable, cleaner, and easier to debug. What’s one useState trick or gotcha you’ve learned? Drop it in the comments #React #JavaScript #WebDevelopment #Frontend #CodingTips

Most React developers focus on writing code. Good developers focus on making it work. But better developers focus on something else: 👉 How often their code runs. A simple mistake I see often: Recomputing values or recreating functions on every render. It works… until scale hits. That’s when performance drops and UI starts lagging. Now I approach React differently: ⚡ Minimize re-renders ⚡ Memoize only where it matters ⚡ Avoid unnecessary calculations ⚡ Think in terms of “cost per render” Because performance is not about speed. It’s about efficiency. What’s one React concept that changed how you write code? #ReactJS #FrontendDevelopment #Performance #JavaScript #CleanCode #SoftwareEngineering

most React developers have too many useEffects. i did too. until i read this rule and couldn't unsee it: if you're using useEffect to sync state with another state you don't need useEffect. here's what i mean. (the pattern 1 .. i see everywhere) but pattern 2 give same result . no effect. no extra render cycle. useEffect is for syncing React with something outside React. - fetching data from an API - setting up a subscription - manually touching the DOM not for calculating values you could just... calculate. every unnecessary useEffect is a hidden render cycle your users pay for. before you write useEffect ask one question: am i syncing with something outside React, or am i just doing math? if it's math delete the effect. #reactjs #typescript #webdevelopment #buildinpublic #javascript

🤔 useMemo and useCallback confuse almost every React developer. Here’s the clearest way to think about it 👇 🧠 Core idea: → useMemo = cache a VALUE → useCallback = cache a FUNCTION REFERENCE 💻 Example: // useMemo — don't recalculate unless deps change const total = useMemo(() => cart.reduce((sum, item) => sum + item.price, 0), [cart] ); // useCallback — don't recreate unless deps change const handleClick = useCallback(() => { doSomething(id); }, [id]); 🎯 When to use useCallback: When you pass a function to a React.memo’d child Without it 👇 ➡️ A new function is created every render ➡️ React.memo becomes useless ⚠️ Common mistake: Wrapping everything in useMemo / useCallback “just in case” 💡 Reality check: Both hooks have a cost Use them only when: ✔️ You’ve identified a real performance issue ✔️ You’ve actually measured it 📌 Rule: Premature optimization ≠ good engineering #ReactJS #Hooks #JavaScript #FrontendDev

🚀 Mastering React Hooks! 🚀 Ever wondered how to manage state in functional components? React Hooks is the answer! They allow you to add state and other React features to functional components without writing a class. Super convenient, right? 🤩 For developers, mastering React Hooks opens up a whole new world of possibilities in simplifying component logic and making code more readable. So let's dive in step by step: 1️⃣ First, import { useState } from 'react' 2️⃣ Then, declare a state variable using useState hook 3️⃣ Use the state variable and a function to update it Here's an example: ```jsx import React, { useState } from 'react'; function Counter() { const [count, setCount] = useState(0); return ( <div> <p>You clicked {count} times</p> <button onClick={() => setCount(count + 1)}>Click me</button> </div> ); } ``` Pro Tip: Remember to always keep the dependencies array updated to avoid unwanted re-renders! 🌟 Common Mistake Alert: Forgetting to pass all dependencies to the dependencies array can lead to unexpected bugs, so be thorough in checking! ❗️ Ready to level up your React game with Hooks? What cool projects are you planning to build using React Hooks? 💡🛠️ #ReactHooks #JavaScript #WebDev #FrontendDevelopment #StateManagement #LearnToCode #CodeNewbie #TechTips #tharindunipun.lk

Starting My React.js Journey – Basics with Code! Today, I revisited the fundamentals of React.js, and I believe mastering the basics is the key to building powerful applications. Sharing a quick snippet that demonstrates how simple and clean React can be import React from "react"; function Welcome() { const name = "Developer"; return ( <div> <h1>Hello, {name} </h1> <p>Welcome to React Basics!</p> </div> ); } export default Welcome; What this covers: - Functional Components - JSX (JavaScript + HTML) - Dynamic Data Rendering using variables Key Learning: React is not just a library — it's a mindset of building reusable and maintainable UI components. Next Steps: - Props & State - Event Handling - Component Lifecycle Consistency beats intensity. Small steps every day = Big growth #ReactJS #WebDevelopment #JavaScript #Frontend #CodingJourney #100DaysOfCode

🚨 Small React mistake… big headache 👇 I used to write code like this without even thinking: if (condition) return null; useEffect(() => { // logic }, []); It looks completely fine, right? I thought the same ❌ Then suddenly this error shows up: 👉 "Rendered fewer hooks than expected" Took me some time to realize what was actually wrong. React expects hooks to run in the same order every single render. But in this case: • First render → component returns early → useEffect doesn’t run • Next render → useEffect runs And boom 💥 React gets confused because the order changed. The fix is simple (but easy to forget): useEffect(() => { // logic }, []); if (condition) return null; Now hooks always run first, no matter what 👍 💡 Lesson learned: Never put hooks after a condition or inside it. Always keep them at the top. Have you ever hit this error? It’s one of those bugs that looks small but wastes a lot of time 😅 #react #nextjs #javascript #frontend #webdev