First IT Internship Interview in Nepal: 25 Real Questions and Beginner-Friendly Answers

### Q1: What is the difference between '==' and '==='? **Answer:** `==` performs type coercion before comparison (e.g., `5 == "5"` is `true`). `===` is strict equality and checks both value and data type without coercion (e.g., `5 === "5"` is `false`). In modern JavaScript, always use `===`. ### Q2: Explain 'let', 'const', and 'var'. **Answer:** - `var`: Function-scoped, can be re-declared and updated, and is hoisted with `undefined`. - `let`: Block-scoped, can be updated but not re-declared in the same scope, and cannot be accessed before declaration (Temporal Dead Zone). - `const`: Block-scoped, cannot be re-declared or reassigned. Objects declared with `const` can still have their properties mutated. ### Q3: What is a Closure in JavaScript? **Answer:** A closure is a function that retains access to variables from its outer (lexical) scope even after the outer function has finished executing. ```javascript function createCounter() { let count = 0; return function() { count++; return count; }; } const counter = createCounter(); console.log(counter()); // 1 console.log(counter()); // 2 ``` ### Q4: Explain the Event Loop and Asynchronous Execution. **Answer:** JavaScript is single-threaded. Synchronous code runs on the Call Stack. Asynchronous tasks (like `fetch` or `setTimeout`) are offloaded to Web APIs. When completed, their callbacks go into the Task Queue (or Microtask Queue for Promises). The **Event Loop** monitors the call stack; once the stack is empty, it pushes tasks from the queue to the stack.

### Q5: What are the main HTTP methods and their idempotency? **Answer:** - `GET`: Retrieve data (Idempotent, Safe). - `POST`: Create new resource (Non-idempotent). - `PUT`: Completely replace an existing resource (Idempotent). - `PATCH`: Partially update a resource. - `DELETE`: Remove a resource (Idempotent). ### Q6: What is the difference between INNER JOIN and LEFT JOIN? **Answer:** - `INNER JOIN`: Returns only rows where there is a match in both tables. - `LEFT JOIN`: Returns all rows from the left table, plus matched records from the right table (with `NULL` for unmatched right table rows). ### Q7: What is CORS and why does the browser enforce it? **Answer:** Cross-Origin Resource Sharing (CORS) is a browser security mechanism that prevents web applications running at one origin from requesting resources from a different origin unless the server explicitly sends `Access-Control-Allow-Origin` headers.

### Q8: 'Tell me about a technical bug you struggled with and how you solved it.' **How to Answer:** Never say *'I haven't faced any difficult bugs.'* Use the STAR framework: 1. **Situation:** *'While deploying my Laravel e-commerce app to cPanel...'* 2. **Task:** *'I was getting a 500 Internal Server Error.'* 3. **Action:** *'Instead of guessing, I inspected `storage/logs/laravel.log`, realized directory permissions were 644, and adjusted permissions to 775 for storage.'* 4. **Result:** *'The site loaded immediately and I documented the deployment checklist on GitHub.'*