Agoda India Frontend Engineer Interview: Rounds, Questions and Preparation

What the job involves

Frontend engineers at global tech companies build and maintain user interfaces for web applications, focusing on performance, accessibility, and cross-browser compatibility. They collaborate with designers, backend engineers, and product managers to deliver features that millions of users interact with daily. The role involves writing clean, testable code, optimizing load times, and ensuring responsive designs.

Frontend Fundamentals

1. 1

   Explain the difference between let, const, and var in JavaScript.

   Cover scoping (block vs function), hoisting, and reassignment rules. Mention temporal dead zone for let/const.

2. 2

   How does the event loop work in JavaScript?

   Describe call stack, task queue, microtasks, and how asynchronous callbacks are executed. Use setTimeout and Promises as examples.

3. 3

   What are semantic HTML elements and why are they important?

   List examples like header, nav, main, article. Explain benefits for accessibility, SEO, and code readability.

4. 4

   Explain CSS box model and how box-sizing affects layout.

   Describe content, padding, border, margin. Contrast content-box vs border-box and give a use case for border-box.

Framework and Tooling

1. 5

   How does React's virtual DOM improve performance?

   Explain diffing algorithm, reconciliation, and how minimal DOM updates reduce reflows. Mention keys in lists.

2. 6

   What are React hooks and why were they introduced?

   Discuss useState, useEffect, and custom hooks. Highlight reuse of stateful logic without classes and simpler code.

3. 7

   How do you manage state in a large React application?

   Compare local state, Context API, and external libraries like Redux or Zustand. Discuss trade-offs and when to use each.

4. 8

   What is the purpose of a build tool like Webpack or Vite?

   Cover bundling, transpiling, minification, code splitting, and hot module replacement. Mention how they improve developer experience and performance.

Practical Scenarios

1. 9

   How would you optimize a web page that takes too long to load?

   Suggest techniques like lazy loading images, code splitting, caching, minifying assets, and using CDNs. Mention measuring with Lighthouse.

2. 10

   You need to make a component accessible to screen readers. What steps do you take?

   Use semantic HTML, ARIA roles and labels, keyboard navigation, and test with screen readers. Mention focus management.

3. 11

   How do you handle cross-browser compatibility issues?

   Discuss feature detection, polyfills, autoprefixer, and testing on multiple browsers. Mention using tools like BrowserStack.

4. 12

   Describe how you would debug a UI bug that only occurs in production.

   Talk about using source maps, logging, error tracking tools (e.g., Sentry), and reproducing with user data. Mention checking network and console.

Behavioural and HR

1. 13

   Tell me about a time you worked in a team to deliver a project.

   Use STAR method. Highlight your role, collaboration, conflict resolution, and outcome. Emphasize communication.

2. 14

   Why do you want to work as a frontend engineer at a global tech company?

   Show passion for user experience, scale, and learning. Connect to company values and products. Avoid generic answers.

3. 15

   How do you keep your frontend skills up to date?

   Mention blogs, newsletters, open source, side projects, and online courses. Show curiosity and continuous learning.

4. 16

   Describe a challenging technical problem you solved and how you approached it.

   Outline the problem, your analysis, solutions considered, and the result. Highlight learning and persistence.