Frontend Developer Interview Questions by Company

A frontend interview is about what the person using the page feels: how fast it opens, whether it works on a slow phone, and whether someone using a keyboard or a screen reader can finish the task. Companies ask the same skills in different clothes, so a shop asks about a product page and a bank asks about a payment form.

What a Frontend Developer interview checks

• How the browser works. What happens between typing an address and seeing the page, what blocks the first paint, and why a page jumps while it loads.
• State and data. Where a value lives, who is allowed to change it, and what the screen shows while the data is still on its way or has failed.
• Speed you can measure. How you find the slow part before you fix it, and how you keep a page fast after the next ten features land.
• Access for everyone. Labels, focus order, contrast and keyboard use, explained as part of building the feature and not as a last step.
• Working with design and backend. How you push back on a design that cannot be built well, and how you agree the shape of an API before either side writes code.

How to prepare

1. Pick two things you built and be ready to draw them: the parts, the data each part owns, and the one decision you would change now.
2. Open one of your own pages on a slow connection and write down what you see. That is a story interviewers rarely hear.
3. Practice saying an answer aloud in about a minute, then the longer version only when asked.
4. Read the company page below for the kind of product they build, and move your examples into that setting.

Mistakes that cost the offer

• Naming a framework as the answer instead of the reason behind the choice.
• Talking about speed without saying how it was measured.
• Treating accessibility as someone else's job.

The rounds of a Frontend Developer interview, and what each one tests

Companies name and order these rounds differently, and a smaller team may cover two in one call. Ask the recruiter which ones you will get.

• Recruiter screen. Your stack, the products you built, why this company. Name what you shipped, not every library you touched.
• JavaScript and browser basics. Closures, the event loop, promises and async code, how this is bound, how the DOM passes events, CSS layout and specificity. Often a few short questions of the kind: what does this code print, and why?
• Machine coding (build a UI). Build a small working component in a fixed time, such as an autocomplete box, tabs, a modal or an endless list. Interviewers watch your structure, your state, the loading and error states, and whether it works with a keyboard.
• Problem solving. Some companies add an algorithm round, mostly arrays, strings, maps and trees. Others swap it for utility functions such as debounce, throttle or a deep copy of an object.
• Frontend system design. Plan the browser side of a news feed, a chat window or a dashboard: components, where state lives, how data is fetched and cached, how it renders, how it stays fast and how it works for everyone. Mostly for mid-level and senior roles.
• Hiring manager or behavioral. Disagreeing with a designer, a bug that reached users, a page you made faster. Bring the result and how you measured it.

A worked Frontend Developer answer: “Build an autocomplete search box. How would you approach it?”

An example spoken answer: “I would start with a few questions: where the suggestions come from, how many to show, and whether it must work on phones. Then I would say the plan before I type.

The input keeps its own text. I would wait until the person pauses typing before calling the API, so every letter does not fire a request. Each request remembers the text it was sent for, and I only show results that match the current text, so a slow old answer cannot replace a newer one.

The list has four states: empty, loading, results and no matches, plus an error message with a retry. For keyboard users, the arrow keys move through the list, Enter picks, Escape closes, and the combobox pattern tells screen readers what is happening. With time left, I would cache recent queries and highlight the matching part of each result.”

Why this Frontend Developer answer works

• It asks about the data and the device before writing code.
• It handles the race between slow and fast responses, which most first attempts miss.
• It names every state the screen can be in, including failure.
• It treats keyboard and screen reader use as part of the build, not an extra.

Brush up the language underneath with the JavaScript interview questions and the React interview questions.

How a Frontend Developer interview changes with your experience

• Fresher or first frontend role. Expect HTML, CSS layout, JavaScript basics and one small build, such as a to-do list or a form that checks its fields. A live project you can explain line by line beats a list of tutorials. Revise the HTML and CSS interview questions first.
• Moving from backend, design or testing. Use what you bring. A backend developer knows APIs and data, a designer knows layout and users, a tester knows edge cases. Then show a frontend project where you handled state, loading and errors yourself.
• Senior frontend. Less trivia, more design: how you would structure a large app, share components across teams, keep pages fast as they grow, and test the interface. Expect at least one frontend system design round.

Frontend Developer interview questions people also ask

What is a machine coding round?

It is a timed round where you build a small working piece of interface, in plain JavaScript or the framework the company uses. You are judged on whether it works, how the code is split, how state is kept, and whether loading, errors and keyboard use are covered. Get a simple version working first, then improve it.

Is DSA asked in frontend interviews?

Some companies ask algorithm questions in a separate round, usually on arrays, strings, hash maps and trees. Others ask for practical JavaScript functions instead, such as debounce, throttle or flattening a nested array. Ask the recruiter which kind you will get, and prepare the basics either way.

What is frontend system design?

It is a design round for the browser side of a product. You plan something like a news feed or a chat app: the components, where data and state live, how data is fetched, cached and updated, how the page stays fast, and how it works for people using a keyboard or a screen reader.

Should I use React or plain JavaScript in the interview?

Use whatever the interviewer allows and you write fastest. Many companies let you choose. When they ask for plain JavaScript, they want to see that you understand the DOM and events without a framework. Build one small component both ways before the interview.