Interview Q&A

Short answer: import axios from 'axios'; jest.mock('axios'); axios.get.mockResolvedValue({ data: 'mock data' });

Example code

import axios from 'axios'; jest.mock('axios'); axios.get.mockResolvedValue({ data: 'mock data' });

Real-world example (ShopNest)

ShopNest’s storefront is React: components for ProductCard, CartDrawer, and CheckoutForm, with hooks for local UI state.

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: React is a JavaScript library for building user interfaces, mainly for single-page applications. It helps developers create reusable UI components, manage state efficiently, and update the UI in a performant way. ✅ Why use React? Easy to break UIs into components Efficient updates with Virtual DOM Rich ecosystem (React Router, Redux, etc.) Backed by Facebook and a large community

Real-world example (ShopNest)

ShopNest’s storefront is React: components for ProductCard, CartDrawer, and CheckoutForm, with hooks for local UI state.

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: on the server. This allows search engines to crawl the content.

Real-world example (ShopNest)

ShopNest’s storefront is React: components for ProductCard, CartDrawer, and CheckoutForm, with hooks for local UI state.

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: dependencies can lead to bugs or infinite loops.

Real-world example (ShopNest)

ShopNest’s cart icon uses useState for count and useEffect to load the cart once on mount.

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 based on props or state.

Real-world example (ShopNest)

ShopNest’s storefront is React: components for ProductCard, CartDrawer, and CheckoutForm, with hooks for local UI state.

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: You can import regular CSS files directly into your components. import './App.css'; // Regular CSS file

Real-world example (ShopNest)

ShopNest’s storefront is React: components for ProductCard, CartDrawer, and CheckoutForm, with hooks for local UI state.

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: assets. It’s highly configurable and can be used for React apps, though tools like CRA automate this.

Real-world example (ShopNest)

ShopNest’s storefront is React: components for ProductCard, CartDrawer, and CheckoutForm, with hooks for local UI state.

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: xios.get.mockResolvedValue({ data: 'mock data' }); xios.get.mockResolvedValue({ data: 'mock data' }); xios.get.mockResolvedValue({ data: 'mock data' }); xios.get.mockResolvedValue({ data: 'mock data' });

Real-world example (ShopNest)

ShopNest’s storefront is React: components for ProductCard, CartDrawer, and CheckoutForm, with hooks for local UI state.

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: Library (for testing React components).

Real-world example (ShopNest)

ShopNest’s storefront is React: components for ProductCard, CartDrawer, and CheckoutForm, with hooks for local UI state.

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 the Profiler tab to measure the render times and identify slow components. Check for unnecessary re-renders and optimize with React.memo or shouldComponentUpdate.

Real-world example (ShopNest)

ShopNest’s storefront is React: components for ProductCard, CartDrawer, and CheckoutForm, with hooks for local UI state.

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: (Don’t call hooks inside loops, conditions, or nested functions.)

Real-world example (ShopNest)

ShopNest’s cart icon uses useState for count and useEffect to load the cart once on mount.

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: React is a JavaScript library for building user interfaces, mainly for single-page applications. It helps developers create reusable UI components, manage state efficiently, and update the UI in a performant way. ✅ Why use React? Easy to break UIs into components Efficient updates with Virtual DOM Rich ecosystem (React Router, Redux, etc.) Backed by Facebook and a large community

Real-world example (ShopNest)

ShopNest’s storefront is React: components for ProductCard, CartDrawer, and CheckoutForm, with hooks for local UI state.

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: import { render } from '@testing-library/react'; import MyComponent from './MyComponent'; test('matches snapshot', () => { const { asFragment } = render(<MyComponent />); expect(asFragment()).toMatchSnapshot(); }); asFragment() captures the rendered output as a DOM snapshot.

Explain a bit more

toMatchSnapshot() compares the output to a previously saved snapshot. The first time the test is run, it saves the output to a snapshot file. On subsequent runs, it compares the output to the saved snapshot. If there are any changes, the test will fail. Advanced React Concepts

Real-world example (ShopNest)

ShopNest’s storefront is React: components for ProductCard, CartDrawer, and CheckoutForm, with hooks for local UI state.

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: import { render, screen, waitFor } from '@testing-library/react'; import MyComponent from './MyComponent'; test('fetches and displays data', async () => { global.fetch = jest.fn(() => Promise.resolve({ json: () => Promise.resolve({ message: 'Data loaded' }), }) ); render(<MyComponent />); await waitFor(() => screen.getByText('Data loaded')); expect(screen.getByText('Data loaded')).toBeInTheDocument(); }); Here, we…

Explain a bit more

mock the fetch function to return mock data, then test whether it appears in the component.

Real-world example (ShopNest)

ShopNest’s storefront is React: components for ProductCard, CartDrawer, and CheckoutForm, with hooks for local UI state.

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: Log the time it takes for certain parts of your app to render and pinpoint slow areas.

Real-world example (ShopNest)

Heavy product grids memoize row components so typing in the search box does not re-render every image card unnecessarily.

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: (ES6+) and JSX syntax in React.

Real-world example (ShopNest)

ShopNest’s storefront is React: components for ProductCard, CartDrawer, and CheckoutForm, with hooks for local UI state.

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: const server = express(); server.get('*', (req, res) => { const content = ReactDOMServer.renderToString(<App />); res.send(` <html> <head><title>SSR Example</title></head> <body> <div id="root">${content}</div> </body> </html> `); }); server.listen(3000, () => console.log('Server running on In this setup, React renders the app to HTML on the server, then the client "hydrates" it for interactivity.

Example code

and making it interactive. Example with express and React: const express = require('express');
const React = require('react');
const ReactDOMServer = require('react-dom/server');
const App = require('./App');

Real-world example (ShopNest)

When rendering cart lines, use a stable key={item.id}—not the array index—so React updates the right row after delete.

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: Example: class ErrorBoundary extends React.Component { constructor(props) { super(props); this.state = { hasError: false }; } static getDerivedStateFromError(error) { return { hasError: true }; // Update state to trigger a fallback UI } componentDidCatch(error, info) { console.error("Error caught by Error Boundary:", error, info); } render() { if (this.state.hasError) { return <h1>Something went wrong!</h1>; }…

Explain a bit more

return this.props.children; } } export default ErrorBoundary; You can wrap parts of your app in this ErrorBoundary to gracefully handle errors.

Example code

Example: class ErrorBoundary extends React.Component { constructor(props) { super(props); this.state = { hasError: false };
} static getDerivedStateFromError(error) { return { hasError: true }; // Update state to trigger a fallback UI } componentDidCatch(error, info) { console.error("Error caught by Error Boundary:", error, info); } render() { if (this.state.hasError) {
return <h1>Something went wrong!</h1>;
}
return this.props.children;
}
} export default ErrorBoundary; You can wrap parts of your app in this ErrorBoundary to gracefully handle errors.

Real-world example (ShopNest)

ShopNest’s storefront is React: components for ProductCard, CartDrawer, and CheckoutForm, with hooks for local UI state.

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: wait waitFor(() => screen.getByText('Data loaded')); expect(screen.getByText('Data loaded')).toBeInTheDocument(); }); Here, we mock the fetch function to return mock data, then test whether it appears in the component.

Explain a bit more

wait waitFor(() => screen.getByText('Data loaded')); expect(screen.getByText('Data loaded')).toBeInTheDocument(); }); Here, we mock the fetch function to return mock data, then test whether it appears in the component. wait waitFor(() => screen.getByText('Data loaded')); expect(screen.getByText('Data loaded')).toBeInTheDocument(); }); Here, we mock the fetch function to return mock data, then test whether it appears in the component.

Real-world example (ShopNest)

ShopNest’s storefront is React: components for ProductCard, CartDrawer, and CheckoutForm, with hooks for local UI state.

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: update only the items that have changed. update only the items that have changed.

Real-world example (ShopNest)

When rendering cart lines, use a stable key={item.id}—not the array index—so React updates the right row after delete.

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 90-day notice is not bad for your career—it is common in Indian IT services. What hurts growth is unplanned exits, burning bridges, or long gaps while serving notice without upskilling. Product companies know service-sector notice norms.

Why this matters in Notice Period

Recruiters ask about notice on the first call. Transparency + early release plan beats hiding your situation.

Step-by-step approach

1. Disclose notice length early in interviews—surprises at offer stage kill deals.
2. Use notice period to finish certifications, portfolio updates, and system design prep.
3. Avoid negative posts about long notice on LinkedIn—frame as “standard for my current employer.”
4. Track release approvals weekly so offers do not expire.
5. If stuck 90 days, negotiate partial remote or learning time with manager.
6. Build relationships during notice—references matter for senior roles.

Real-world example

Ananya served full 90 days at Cognizant but used evenings for Azure certification and mock interviews. She joined Zoho with a clear story: “I honored commitment, automated handover, and upskilled.” Interviewers valued reliability over speed.

Mistakes to avoid

• Believing only 15-day notice companies are “good”—many strong firms accept 90 with planning.
• Going idle during notice—recruiters notice skill rust in later rounds.
• Accepting counter-offers without fixing why you wanted to leave.
• Letting frustration show in team meetings during long notice.

Follow-up questions you may get

• “Can you join in 30 days?” — Explain actual notice + KT plan + possible buyout.
• “Why is your notice so long?” — Industry norm for service co; not a performance issue.

Growth comes from skills and outcomes, not notice length alone—use the window deliberately.

Short answer: Resign in person or video call to your manager first, then submit formal email to HR the same day. Stay positive, give adequate notice, and focus on handover—not grievances. Professional exits protect references and future background checks.

Step-by-step approach

1. Choose timing: avoid peak release week unless unavoidable; give manager heads-up privately.
2. Prepare resignation letter/email before the conversation.
3. Thank manager for growth; state last working day per contract.
4. Ask about handover expectations and exit formalities (assets, access, exit interview).
5. Inform HR via official channel; complete separation portal steps.
6. Remain productive; do not download client data or solicit colleagues to leave.

Real-world example

Neha met her manager on Monday morning, explained she accepted a product role, and shared a 2-week handover outline. She submitted HR resignation by noon, completed exit checklist, and received a positive experience letter mentioning “professional conduct during transition.”

Mistakes to avoid

• Resigning by email without speaking to manager first.
• Using resignation to negotiate salary unless you will genuinely stay.
• Telling teammates before manager—news travels and erodes trust.
• Deleting code or docs out of frustration—can be grounds for legal action.

Toolliyo resources

• Update resume before exit interviews
• More career Q&A

You can be firm and kind: “This was a hard decision; I want to make the transition smooth for the team.”

Short answer: Keep it short: intent to resign, last working day per policy, gratitude, and offer to support handover. Do not include reasons for leaving, complaints, or new employer name unless required.

Step-by-step approach

1. Address manager and HR (or use company resignation template).
2. State: “I hereby resign from my position as [title], effective [resignation date].”
3. Mention contractual notice and proposed LWD.
4. Thank the organization; offer KT support.
5. Sign with full name, employee ID, contact.
6. Attach formal letter PDF if HR requires it.

Real-world example

Arjun sent a 6-line email after a manager call. HR accepted immediately; no back-and-forth because dates matched policy and tone was neutral. His F&F processed on time.

What to say / email template

Subject: Resignation — [Your Full Name] — [Employee ID]

Dear [Manager Name] and HR Team,

Please accept this email as formal notice of my resignation from the position of [Job Title], effective [Resignation Date].

As per my employment terms, my notice period is [X days/weeks], and my expected last working day is [LWD], subject to company policy and handover completion.

I am grateful for the opportunities here and will do my best to ensure a smooth transition, including documentation and knowledge transfer.

Please advise on exit formalities and asset return.

Sincerely,
[Full Name]
[Employee ID]
[Phone]

Mistakes to avoid

• Writing a novel about why you hate the job.
• Naming the new company and salary—creates unnecessary friction.
• Wrong LWD math—HR will ask you to resubmit and delay process.
• Sending from personal email instead of corporate account.

Save a PDF copy—needed for visa, loans, and future verification.

Short answer: If your contract specifies notice and you resign voluntarily, the employer can require you to serve it or pay buyout if allowed. They generally cannot force unpaid labor beyond contract, but absconding triggers recovery clauses and legal risk.

Why this matters in Notice Period

Indian employment law is contract-driven. IT industry norms are strong but not above written terms.

Step-by-step approach

1. Re-read appointment letter, bond (if any), and separation policy.
2. Understand consequences of not serving: salary hold, experience letter delay, negative verification.
3. If employer denies release without cause, escalate to HRBP with documented KT proof.
4. Consult labor lawyer only for clear violations (harassment, withheld salary illegally)—rare for standard notice disputes.
5. Never stop working without formal acceptance of absconding consequences.
6. Negotiate buyout or partial serve if full 90 days is impossible for new offer.

Real-world example

A developer’s manager refused early release despite empty backlog. HR cited policy: full 60 days or buyout. He chose buyout funded by new employer rather than absconding—avoided blacklist on background verification vendors used by top product firms.

Numbers & benchmarks

• Background verification failures on notice absconding can delay offers 2–8 weeks.
• Recovery claims: typically basic salary for unserved days plus statutory adjustments.

Mistakes to avoid

• Assuming “I can leave anytime” in at-will myths—India is not US at-will for most IT contracts.
• Absconding to join startup—many vendors flag “did not serve notice.”
• Threatening legal action without grounds—burns references.
• Ignoring garden leave instructions while working elsewhere.

If stuck, serve professionally—your reputation outlasts one long notice.

Short answer: Leaving without notice (absconding) usually triggers salary forfeiture, negative or delayed experience letter, recovery notices, and failed background checks. Some employers mark “not eligible for rehire.” New employers may revoke offers if verification fails.

Step-by-step approach

1. Calculate total cost: recovery letter + legal fees + offer loss vs buyout cost.
2. Contact old HR to negotiate settlement—even after leaving—some accept buyout late.
3. Document any harassment or illegal withholding if that forced exit (seek legal advice).
4. Prepare honest explanation for future employers—avoid lying on verification forms.
5. Complete PF/gratuity transfer separately—absconding complicates but does not always block PF.
6. Rebuild trust with strong references from other managers/clients if possible.

Real-world example

Karthik absconded from a service firm after 20 days of 90-day notice to join a startup. BGV failed; startup withdrew offer. He paid settlement after 6 months, got experience letter, and re-applied—lost a year of seniority progression. Buyout would have cost less than career damage.

Mistakes to avoid

• Believing small companies “do not check” notice history—they use third-party BGV.
• Ignoring recovery emails—accumulates interest and legal escalation in some cases.
• Using fake experience letters—criminal fraud risk.
• Assuming new employer will always protect you—they protect their hiring compliance first.

Follow-up questions you may get

• “Why did you leave abruptly?” — Own mistake, explain settlement, emphasize reliability since then.

Almost always cheaper and safer to negotiate buyout or serve partial notice than to abscond.