ES6 full form

👉 ECMAScript 2015 ECMAScript full form: 👉 European Computer Manufacturers Association Script Explanation: 👉 ECMAScript is the standard on which JavaScript is based. Simple Line: 👉 ECMAScript = Standard version of JavaScript defined by ECMA organization Explanation: Simple Line: 👉 ES6 = ECMAScript 6 (ECMAScript 2015)

1️⃣ let & const 🔹 let 🔹 const 2️⃣ Arrow Functions (=>) Shorter way to write functions. Normal Function Arrow Function With one parameter 3️⃣ Template Literals ( ) Use backticks instead of quotes → allows variables & multi-line strings. Multi-line let text = `Line 1Line 2Line 3`; 4️⃣ Destructuring Extract values from arrays/objects easily. […]

1️⃣ What is an API? API = Application Programming Interface 👉 It allows two applications to communicate with each other. Example: 👉 Like a waiter: 2️⃣ Fetch API fetch() is used to get data from APIs Basic Syntax: Modern (Async/Await): 3️⃣ JSON (JavaScript Object Notation) 👉 Most APIs return data in JSON format Example JSON: […]

🔥 Async JavaScript – Interview Questions 🟢 Basic Level (1–7) 1. What is Asynchronous JavaScript? 👉 JavaScript that allows tasks to run in the background without blocking the main thread. 2. Difference between synchronous and asynchronous? 3. What is setTimeout()? 👉 Runs a function once after a specified delay. 4. What is setInterval()? 👉 Runs […]

1. Synchronous vs Asynchronous ✅ Synchronous (Blocking) Code runs line by line, one after another. 👉 Output: StartMiddleEnd Everything waits for the previous line to finish. ⚡ Asynchronous (Non-blocking) Some tasks take time (API calls, timers). JS sends them to the background and continues execution. 👉 Output: StartEndMiddle 👉 JS doesn’t wait for setTimeout. 2. […]

Real Company-Level JavaScript Questions 1️⃣ (Amazon) – Closure + Loop Trap ❓ Output: 5 5 5 5 5 💡 Why? var is function-scoped → same i shared ✅ Fix: 2️⃣ (Google) – Event Loop Priority ❓ Output: ADCB 💡 Why? Microtasks (Promise) run before macrotasks (setTimeout) 3️⃣ (Amazon) – this Binding ❓ Output: undefined 💡 […]

1️⃣ Hoisting + var Output: undefined Why?var a is hoisted → initialized with undefined 2️⃣ Hoisting + let Output: ReferenceError Why?let is in Temporal Dead Zone 3️⃣ Function vs Variable Hoisting Output: 10 Why?Function is hoisted first, but var a = 10 overrides it 4️⃣ Closure Trick Output: 11 Why?Closure remembers a 5️⃣ setTimeout + […]

1️⃣ What is Scope in JavaScript? Answer:Scope determines where variables are accessible. 👉 b is not accessible outside the function. 2️⃣ What is Hoisting? Answer:Hoisting is JavaScript’s default behavior of moving declarations to the top. 👉 var is hoisted with undefined ⚠️ let and const are hoisted but in Temporal Dead Zone 3️⃣ What is […]

1️⃣ Scope Scope defines where variables are accessible in your code. Types: 👉 c is NOT accessible outside block. 2️⃣ Hoisting Hoisting means variables and functions are moved to the top of their scope during execution. Internally becomes: ⚠️ Important: 3️⃣ Closures Closure = function + its lexical environment A function remembers variables from its […]

🧪 JavaScript Events – Practice Questions 🟢 Beginner Level (1–7) 1. Create a button. When clicked, change its text to “Clicked!”. 2. Create a button that shows an alert message when double-clicked. 3. Create a div. Change its background color when mouse hovers over it. 4. Create an input box. Display text “Typing…” when user […]