Interview Q&A

Short answer: Decorators modify classes or methods at runtime. Common in TypeScript and frameworks like Angular. Example (TypeScript): function log(target, key) { console.log(`${key} was called`); }

Example code

class Example { @log test() {} }

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: Promise chaining allows multiple async tasks to run sequentially.

Example code

fetch('/data') .then(res => res.json()) .then(data => console.log(data)) .catch(err => console.error(err));

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: DOM (Document Object Model) represents the structure of an HTML document as a tree of objects, allowing JavaScript to access and manipulate elements dynamically. 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: Define a variable with --name and access it with var().

Example code

:root { -main-color: #007bff; -padding: 10px; } button { background: var(--main-color); padding: var(--padding); } Follow me on LinkedIn: Key Takeaway: CSS variables make styles dynamic and reusable.

Real-world example (ShopNest)

In ShopNest’s cart UI, a click handler closes over productId. Use let in loops so each button keeps the correct id.

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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: <b> only makes text bold visually. <strong> adds semantic meaning (important text). Example: <b>Warning:</b> Incorrect password.<br> <strong>Warning:</strong> Incorrect password. Key Takeaway: Use <strong> for emphasis that affects meaning.

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: A function passed as an argument to another function to be executed later. Example: function greet(name, callback) { console.log(`Hello, ${name}`); callback(); }

Example code

greet("Sandeep", () => console.log("Callback executed"));

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: Provides consistent button styling: <button class="btn btn-primary">Click</button>

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: Using prototypes or classes. Example (ES6): class Animal { eat() { console.log("Eating"); } } class Dog extends Animal { bark() { console.log("Bark!"); } Follow me on LinkedIn: }

Example code

Using prototypes or classes. Example (ES6): class Animal { eat() { console.log("Eating"); } }
class Dog extends Animal { bark() { console.log("Bark!"); } 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: They are collections that hold weak references to objects — allowing garbage collection if no other reference exists. Example: let obj = {}; let wm = new WeakMap(); wm.set(obj, "value"); obj = null; // entry removed automatically

Example code

They are collections that hold weak references to objects — allowing garbage collection if no other reference exists. Example: let obj = {};
let wm = new WeakMap(); wm.set(obj, "value"); obj = null; // entry removed automatically

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: JSON (JavaScript Object Notation) is a lightweight format for storing and transferring data. Example: let obj = { name: "Bob" }; let json = JSON.stringify(obj); // Convert to JSON string

Example code

JSON (JavaScript Object Notation) is a lightweight format for storing and transferring data. Example: let obj = { name: "Bob" };
let json = JSON.stringify(obj); // Convert to JSON string

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: Media queries apply styles based on device conditions (width, orientation, etc.).

Example code

@media (max-width: 768px) { body { background-color: lightgray; } } Key Takeaway: Media queries enable responsive design across devices.

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: <i> makes text italic for style only. <em> gives emphasis that can change meaning. Example: <i>Book titles</i> are italicized. Please <em>do not</em> touch that. Follow me on LinkedIn: Key Takeaway: <em> adds importance — <i> adds 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: A function that: Always returns the same output for the same input Has no side effects (doesn’t modify external variables) Example: function sum(a, b) { return a + b;

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: Styled inputs, selects, and textareas: <input type="text" class="form-control" placeholder="Enter name">

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: Async iterators allow looping over asynchronous data sources. Example: async function* fetchItems() { yield await fetch('/item1'); yield await fetch('/item2'); } for await (let item of fetchItems()) { console.log(item); }

Example code

Async iterators allow looping over asynchronous data sources. Example: async function* fetchItems() { yield await fetch('/item1'); yield await fetch('/item2'); }
for await (let item of fetchItems()) { console.log(item); }

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: Method Mutates Original? Purpose slice(start, end) ❌ No Extracts portion Follow me on LinkedIn: splice(start, count, ...items) ✅ Yes Adds/removes items

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: localStorage stores key-value pairs in the browser permanently (until cleared).

Example code

localStorage.setItem("user", "Alice"); console.log(localStorage.getItem("user")); // Alice

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: float moves elements to the left or right — allowing text and inline elements to wrap around.

Example code

img { float: right; margin: 10px; } Key Takeaway: Used for text wrapping, but Flexbox/Grid is better for layout today.

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: A favicon is the small icon shown in the browser tab.

Example code

<link rel="icon" type="image/png" href="favicon.png"> Key Takeaway: Favicons help brand your site in the browser.

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: A function that calls itself until a base condition is met. Example: function factorial(n) { if (n === 0) return 1; return n * factorial(n - 1); } console.log(factorial(5)); // 120

Example code

A function that calls itself until a base condition is met. Example: function factorial(n) { if (n === 0) return 1;
return n * factorial(n - 1);
} console.log(factorial(5)); // 120

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: dvanced What is the difference between order and offset classes? order-*: Changes element order in flex containers. .offset-*: Adds left margin space in grids. <div class="col-md-4 order-2 offset-md-1"></div> 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: Use Flexbox utilities: <div class="d-flex align-items-center" style="height:200px;"> <p>Vertically centered</p> </div> Advanced What is the difference between order and offset classes? .order-*: Changes element order in flex containers. .offset-*: Adds left margin space in grids. <div class="col-md-4 order-2 offset-md-1"></div> 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: Type Example Priority Microtask Promise.then, MutationObserver Higher Macrotask setTimeout, setInterval Lower Example: setTimeout(() => console.log("Macro"), 0);

Example code

Promise.resolve().then(() => console.log("Micro")); // Output: Micro → Macro

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: Mutable: Can be changed after creation (e.g., arrays, objects). Immutable: Cannot be changed once created (e.g., strings, numbers).

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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: It allows unpacking values from arrays or objects. Example: const [a, b] = [1, 2]; const { name, age } = { name: "John", age: 30 };

Example code

It allows unpacking values from arrays or objects. Example: const [a, b] = [1, 2];
const { name, age } = { name: "John", age: 30 };

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.