🚨 𝗪𝗵𝘆 𝟵𝟬% 𝗼𝗳 𝗖𝗮𝗻𝗱𝗶𝗱𝗮𝘁𝗲𝘀 𝗙𝗮𝗶𝗹 𝗧𝗵𝗶𝘀 𝗝𝗮𝘃𝗮𝗦𝗰𝗿𝗶𝗽𝘁 𝗜𝗻𝘁𝗲𝗿𝘃𝗶𝗲𝘄 𝗤𝘂𝗲𝘀𝘁𝗶𝗼𝗻 𝗧𝗵𝗶𝘀 𝗢𝗡𝗘 𝗾𝘂𝗲𝘀𝘁𝗶𝗼𝗻 𝗵𝗮𝘀 𝗿𝗲𝗷𝗲𝗰𝘁𝗲𝗱 𝗺𝗼𝗿𝗲 𝗳𝗿𝗼𝗻𝘁𝗲𝗻𝗱 𝗰𝗮𝗻𝗱𝗶𝗱𝗮𝘁𝗲𝘀 𝘁𝗵𝗮𝗻 𝗮𝗻𝘆 𝗼𝘁𝗵𝗲𝗿. And it's not even that hard once you understand it. I'm talking about 𝗖𝗹𝗼𝘀𝘂𝗿𝗲𝘀. Let me break it down so you NEVER fail this again 👇 📖 𝗪𝗛𝗔𝗧 𝗜𝗦 𝗔 𝗖𝗟𝗢𝗦𝗨𝗥𝗘? A closure is when a function "remembers" variables from its outer scope, even after the outer function has finished executing. 💻 𝗘𝗫𝗔𝗠𝗣𝗟𝗘 𝟭: 𝗗𝗮𝘁𝗮 𝗣𝗿𝗶𝘃𝗮𝗰𝘆 𝘧𝘶𝘯𝘤𝘵𝘪𝘰𝘯 𝘤𝘳𝘦𝘢𝘵𝘦𝘉𝘢𝘯𝘬𝘈𝘤𝘤𝘰𝘶𝘯𝘵(𝘪𝘯𝘪𝘵𝘪𝘢𝘭) { 𝘭𝘦𝘵 𝘣𝘢𝘭𝘢𝘯𝘤𝘦 = 𝘪𝘯𝘪𝘵𝘪𝘢𝘭; // 𝘗𝘙𝘐𝘝𝘈𝘛𝘌 𝘷𝘢𝘳𝘪𝘢𝘣𝘭𝘦! 𝘳𝘦𝘵𝘶𝘳𝘯 { 𝘥𝘦𝘱𝘰𝘴𝘪𝘵: (𝘢𝘮𝘰𝘶𝘯𝘵) => 𝘣𝘢𝘭𝘢𝘯𝘤𝘦 += 𝘢𝘮𝘰𝘶𝘯𝘵, 𝘸𝘪𝘵𝘩𝘥𝘳𝘢𝘸: (𝘢𝘮𝘰𝘶𝘯𝘵) => 𝘣𝘢𝘭𝘢𝘯𝘤𝘦 -= 𝘢𝘮𝘰𝘶𝘯𝘵, 𝘨𝘦𝘵𝘉𝘢𝘭𝘢𝘯𝘤𝘦: () => 𝘣𝘢𝘭𝘢𝘯𝘤𝘦 }; } 𝘤𝘰𝘯𝘴𝘵 𝘢𝘤𝘤𝘰𝘶𝘯𝘵 = 𝘤𝘳𝘦𝘢𝘵𝘦𝘉𝘢𝘯𝘬𝘈𝘤𝘤𝘰𝘶𝘯𝘵(1000); 𝘢𝘤𝘤𝘰𝘶𝘯𝘵.𝘥𝘦𝘱𝘰𝘴𝘪𝘵(500); 𝘤𝘰𝘯𝘴𝘰𝘭𝘦.𝘭𝘰𝘨(𝘢𝘤𝘤𝘰𝘶𝘯𝘵.𝘨𝘦𝘵𝘉𝘢𝘭𝘢𝘯𝘤𝘦()); // 1500 // ❌ 𝘊𝘢𝘯'𝘵 𝘢𝘤𝘤𝘦𝘴𝘴 𝘥𝘪𝘳𝘦𝘤𝘵𝘭𝘺 - 𝘪𝘵'𝘴 𝘱𝘳𝘰𝘵𝘦𝘤𝘵𝘦𝘥! 𝘤𝘰𝘯𝘴𝘰𝘭𝘦.𝘭𝘰𝘨(𝘢𝘤𝘤𝘰𝘶𝘯𝘵.𝘣𝘢𝘭𝘢𝘯𝘤𝘦); // 𝘶𝘯𝘥𝘦𝘧𝘪𝘯𝘦𝘥 𝗪𝗵𝘆 𝗶𝘁 𝗺𝗮𝘁𝘁𝗲𝗿𝘀: This is how we create private variables in JavaScript. React's useState works on similar principles! 🎯 WHERE CLOSURES ARE USED: ✅ React Hooks (useState, useEffect) ✅ Event Handlers ✅ Callbacks & Async Code ✅ Module Pattern ✅ Memoization ✅ Debounce & Throttle ✅ Currying ⚠️ WATCH OUT FOR: ❌ Memory leaks (closures keep variables alive) ❌ Stale closures in React useEffect ❌ var in loops (use let instead) 𝗦𝗮𝘃𝗲 𝘁𝗵𝗶𝘀. 𝗣𝗿𝗮𝗰𝘁𝗶𝗰𝗲 𝘁𝗵𝗲𝘀𝗲 𝗲𝘅𝗮𝗺𝗽𝗹𝗲𝘀. 𝗡𝗮𝗶𝗹 𝘆𝗼𝘂𝗿 𝗶𝗻𝘁𝗲𝗿𝘃𝗶𝗲𝘄. 🎯 𝙒𝙖𝙣𝙩 𝙙𝙚𝙩𝙖𝙞𝙡𝙚𝙙 𝙚𝙭𝙥𝙡𝙖𝙣𝙖𝙩𝙞𝙤𝙣 𝙤𝙣 𝘿𝙖𝙩𝙖 𝙋𝙧𝙞𝙫𝙖𝙘𝙮 𝙤𝙧 𝘿𝙚𝙗𝙤𝙪𝙣𝙘𝙚?𝘾𝙤𝙢𝙢𝙚𝙣𝙩 𝙗𝙚𝙡𝙤𝙬!👇 ♻️ 𝙍𝙚𝙥𝙤𝙨𝙩 𝙖𝙣𝙙 𝙘𝙤𝙢𝙢𝙚𝙣𝙩 𝙩𝙤 𝙝𝙚𝙡𝙥 𝙨𝙤𝙢𝙚𝙤𝙣𝙚 𝙥𝙧𝙚𝙥𝙖𝙧𝙞𝙣𝙜 𝙛𝙤𝙧 𝙞𝙣𝙩𝙚𝙧𝙫𝙞𝙚𝙬𝙨 💾 𝙎𝙖𝙫𝙚 𝙛𝙤𝙧 𝙮𝙤𝙪𝙧 𝙣𝙚𝙭𝙩 𝙞𝙣𝙩𝙚𝙧𝙫𝙞𝙚𝙬 #FrontendInterview #JavaScript #WebDeveloper #ReactJS #Closures #InterviewQuestions #TechInterview #CodingInterview #FrontendDeveloper #SoftwareEngineer #100DaysOfCode #WebDevelopment
Insightful Ajay Sharma 👍
Insightful Ajay Sharma