Interview Q&A

Short answer: String, Number, Boolean, Undefined, Null, BigInt, Symbol String, Number, Boolean, Undefined, Null, BigInt, Symbol String, Number, Boolean, Undefined, Null, BigInt, Symbol String, Number, Boolean, Undefined, Null, BigInt, Symbol String, Number, Boolean, Undefined, Null, BigInt, Symbol String, Number, Boolean, Undefined, Null, BigInt, Symbol String, Number, Boolean, Undefined, Null, BigInt, Symbol String, Number,…

Example code

String, Number, Boolean, Undefined, Null, BigInt, Symbol String, Number, Boolean, Undefined, Null, BigInt, Symbol String, Number, Boolean, Undefined, Null, BigInt, Symbol String, Number, Boolean, Undefined, Null, BigInt, Symbol String, Number, Boolean, Undefined, Null, BigInt, Symbol String, Number, Boolean, Undefined, Null, BigInt, Symbol String, Number, Boolean, Undefined, Null, BigInt, Symbol String, Number, Boolean, Undefined, Null, BigInt, Symbol

Real-world example (ShopNest)

ShopNest’s browser cart uses modern JavaScript: fetch APIs with async/await, modules, and clear error handling.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: They are part of the browser’s rendering process when the DOM or styles change.

Explain a bit more

Reflow (Layout): Happens when the structure or geometry of the page changes (like changing size, position, or adding elements). → Expensive operation since it recalculates layout. Follow me on LinkedIn: Repaint: Happens when visual appearance (like color or background) changes without affecting layout. Example: div.style.width = "200px"; /* triggers reflow + repaint */

Example code

div.style.background = "red"; /* triggers repaint only */ Key Takeaway: Minimize layout changes; batch DOM updates to improve performance.

Real-world example (ShopNest)

ShopNest’s browser cart uses modern JavaScript: fetch APIs with async/await, modules, and clear error handling.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: block elements take full width and start on a new line. inline-block behaves like inline (stays in the same line) but allows setting width, height, margin, and padding.

Example code

.block { display: block; width: 100px; } .inline-block { display: inline-block; width: 100px; } Key Takeaway: inline-block combines the flow of inline with the flexibility of block. Follow me on LinkedIn:

Real-world example (ShopNest)

ShopNest’s browser cart uses modern JavaScript: fetch APIs with async/await, modules, and clear error handling.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: .highlight { background: yellow; } .highlight { background: yellow; } .highlight { background: yellow; } .highlight { background: yellow; } .highlight { background: yellow; } .highlight { background: yellow; } .highlight { background: yellow; } .highlight { background: yellow; }

Real-world example (ShopNest)

ShopNest’s browser cart uses modern JavaScript: fetch APIs with async/await, modules, and clear error handling.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: <style> p { color: blue; } </style> <style> p { color: blue; } </style> <style> p { color: blue; } </style> <style> p { color: blue; } </style> <style> p { color: blue; } </style> <style> p { color: blue; } </style> <style> p { color: blue; } </style> <style> p { color: blue; } </style>

Real-world example (ShopNest)

ShopNest’s browser cart uses modern JavaScript: fetch APIs with async/await, modules, and clear error handling.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: The browser reads HTML line-by-line and builds a DOM (Document Object Model) tree.

Real-world example (ShopNest)

ShopNest’s browser cart uses modern JavaScript: fetch APIs with async/await, modules, and clear error handling.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: When a browser loads a webpage, it goes through these main steps:

Real-world example (ShopNest)

ShopNest’s browser cart uses modern JavaScript: fetch APIs with async/await, modules, and clear error handling.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: JavaScript is a high-level, interpreted programming language primarily used for web development to make webpages interactive. Example: alert('Hello World!');

Example code

JavaScript is a high-level, interpreted programming language primarily used for web development to make webpages interactive. Example: alert('Hello World!');

Real-world example (ShopNest)

ShopNest’s browser cart uses modern JavaScript: fetch APIs with async/await, modules, and clear error handling.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: ✅ Responsive design ✅ Pre-styled components ✅ Cross-browser compatibility ✅ Customizable via variables and themes ✅ Speeds up development

Real-world example (ShopNest)

ShopNest’s browser cart uses modern JavaScript: fetch APIs with async/await, modules, and clear error handling.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: V8 is Google’s open-source JavaScript engine used in Chrome and Node.js. It:

Real-world example (ShopNest)

ShopNest’s browser cart uses modern JavaScript: fetch APIs with async/await, modules, and clear error handling.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: The event loop manages asynchronous operations in JavaScript. It continuously checks the call stack and callback queue — executing queued tasks once the stack is empty.

Example code

console.log("A"); setTimeout(() => console.log("B"), 0); console.log("C"); // Output: A, C, B Even though setTimeout is 0ms, it runs after the main thread finishes due to the event loop.

Real-world example (ShopNest)

The checkout button uses async/await to call /api/orders, shows a spinner, and catches network errors with a toast.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Object (includes Arrays, Functions, Dates, etc.)

Real-world example (ShopNest)

ShopNest’s browser cart uses modern JavaScript: fetch APIs with async/await, modules, and clear error handling.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: ✅ Best Practices: Minimize reflows/repaints by avoiding inline styles or frequent layout changes.

Explain a bit more

Use transform and opacity for animations (GPU-accelerated). Combine and minify CSS files. Use specific selectors, not overly complex ones (div ul li a {...} = costly). Avoid large background images or unnecessary CSS rules. Use modern layout methods (Flexbox/Grid) efficiently. Key Takeaway: Efficient CSS = fewer reflows, fewer repaints, and lightweight selectors.

Real-world example (ShopNest)

ShopNest’s browser cart uses modern JavaScript: fetch APIs with async/await, modules, and clear error handling.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Flexbox (Flexible Box Layout) is a one-dimensional layout system for aligning items horizontally or vertically.

Example code

.container { display: flex; justify-content: center; align-items: center; } Why use it: Centers elements easily. Handles spacing and alignment dynamically. Makes layouts responsive. Key Takeaway: Flexbox simplifies alignment and space distribution in one direction.

Real-world example (ShopNest)

ShopNest’s browser cart uses modern JavaScript: fetch APIs with async/await, modules, and clear error handling.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: #main { width: 80%; } #main { width: 80%; } #main { width: 80%; } #main { width: 80%; } #main { width: 80%; } #main { width: 80%; } #main { width: 80%; } #main { width: 80%; }

Real-world example (ShopNest)

ShopNest’s browser cart uses modern JavaScript: fetch APIs with async/await, modules, and clear error handling.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: <link rel="stylesheet" href="styles.css">

Real-world example (ShopNest)

ShopNest’s browser cart uses modern JavaScript: fetch APIs with async/await, modules, and clear error handling.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: There are three ways to include CSS: Inline CSS: <p style="color: blue;">Hello!</p>

Example code

There are three ways to include CSS: Inline CSS: <p style="color: blue;">Hello!</p>

Real-world example (ShopNest)

ShopNest’s browser cart uses modern JavaScript: fetch APIs with async/await, modules, and clear error handling.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: ARIA (Accessible Rich Internet Applications) roles make web content more accessible for users relying on assistive technologies (like screen readers).

Example code

<button role="switch" aria-checked="false">Dark Mode</button> role="switch" defines what the element represents. Follow me on LinkedIn: aria-checked communicates the state to assistive devices. Key Takeaway: ARIA makes dynamic interfaces accessible by adding semantic meaning beyond native HTML.

Real-world example (ShopNest)

ShopNest’s browser cart uses modern JavaScript: fetch APIs with async/await, modules, and clear error handling.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: CSS is parsed into a CSSOM (CSS Object Model). JavaScript may modify the DOM or halt parsing (especially with synchronous scripts).

Real-world example (ShopNest)

ShopNest’s browser cart uses modern JavaScript: fetch APIs with async/await, modules, and clear error handling.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: The <!DOCTYPE html> declaration tells the browser which version of HTML the page uses. In modern websites, it triggers HTML5 standards mode, ensuring consistent rendering across browsers. Example: <!DOCTYPE html> <html> ... </html> Key Takeaway: Always include <!DOCTYPE html> at the top of every HTML file.

Real-world example (ShopNest)

ShopNest’s browser cart uses modern JavaScript: fetch APIs with async/await, modules, and clear error handling.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: JavaScript is interpreted, runs mainly in browsers. Java is compiled, runs on JVM. Syntax differs, and Java is strongly typed, JS is dynamically typed.

Real-world example (ShopNest)

ShopNest’s browser cart uses modern JavaScript: fetch APIs with async/await, modules, and clear error handling.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: lignment Easier for single direction Easier for full layout structure /* Flexbox */ display: flex; /* Grid */ Follow me on LinkedIn: display: grid; grid-template-columns: repeat(3, 1fr); Key Takeaway: Use Flexbox for alignment; Grid for complete layouts. lignment Easier for single direction Easier for full layout structure

Example code

/* Flexbox */ display: flex; /* Grid */ Follow me on LinkedIn: display: grid; grid-template-columns: repeat(3, 1fr); Key Takeaway: Use Flexbox for alignment; Grid for complete layouts. lignment Easier for single direction Easier for full layout structure Example: /* Flexbox */ display: flex; /* Grid */ Follow me on LinkedIn: display: grid; grid-template-columns: repeat(3, 1fr); Key Takeaway: Use Flexbox for alignment; Grid for complete layouts.

Real-world example (ShopNest)

ShopNest’s browser cart uses modern JavaScript: fetch APIs with async/await, modules, and clear error handling.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Feature Bootstrap 4 Bootstrap 5 jQuery Required Removed Grid 5 breakpoints 6 (added xxl) Forms Legacy Redesigned Icons None Separate Bootstrap Icons Utility API Limited Expanded and customizable

Real-world example (ShopNest)

ShopNest’s browser cart uses modern JavaScript: fetch APIs with async/await, modules, and clear error handling.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Garbage collection automatically frees memory that’s no longer referenced. The V8 engine uses the mark-and-sweep algorithm: “Mark” reachable objects from the root. “Sweep” and delete unreachable ones. Example: let user = { name: "John" };

Example code

user = null; // eligible for garbage collection

Real-world example (ShopNest)

ShopNest’s browser cart uses modern JavaScript: fetch APIs with async/await, modules, and clear error handling.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Follow me on LinkedIn:

Real-world example (ShopNest)

ShopNest’s browser cart uses modern JavaScript: fetch APIs with async/await, modules, and clear error handling.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.