*Coding interview questions with concise answers for software roles*: *1️⃣ What happens when you type a URL and hit Enter?* *Answer:* - DNS Lookup → IP address - Browser sends HTTP/HTTPS request - Server responds with HTML/CSS/JS - Browser builds DOM, applies styles (CSSOM), runs JS - Page is rendered *2️⃣ Difference between var, let, and const?* *Answer:* - `var`: function-scoped, hoisted - `let`: block-scoped, not hoisted - `const`: block-scoped, can’t be reassigned *3️⃣ Reverse a String in JavaScript* ```js function reverseString(str) { return str.split('').reverse().join(''); } ``` *4️⃣ Find the max number in an array* ```js const max = Math.max(...arr); ``` *5️⃣ Write a function to check if a number is prime* ```js function isPrime(n) { if (n < 2) return false; for (let i = 2; i <= Math.sqrt(n); i++) { if (n % i === 0) return false; } return true; } ``` *6️⃣ What is closure in JavaScript?* *Answer:* A function that remembers variables from its outer scope even after the outer function has returned. *7️⃣ What is event delegation?* *Answer:* Attaching a single event listener to a parent element to manage events on its children using `event.target`. *8️⃣ Difference between == and ===* *Answer:* - `==` checks value (with type coercion) - `===` checks value + type (strict comparison) *9️⃣ What is the Virtual DOM?* *Answer:* A lightweight copy of the real DOM used in React. React updates the virtual DOM first and then applies only the changes to the real DOM for efficiency. *🔟 Write code to remove duplicates from an array* ```js const uniqueArr = [...new Set(arr)]; ``` *React ❤️ for more*