Frontend Interview Questions

Frontend development questions covering HTML, CSS, JavaScript, browser APIs, performance optimization, and UI/UX implementation.

Related:react nodejs

16

Questions in database

Questions (16)

EasyPhone Screen

2

234

What is the difference between == and === in JavaScript?

Explain the difference between loose equality (==) and strict equality (===) operators in JavaScript. When would you use one over the other?

Frontend Node.js

Software Engineer

EasyPhone Screen

2

312

What are closures in JavaScript?

Explain what closures are in JavaScript. Provide an example of when you would use a closure and explain how it works.

Frontend Node.js

Frontend Engineer

MediumTechnical

2

198

Explain React useCallback vs useMemo

What are the differences between useCallback and useMemo hooks in React? When would you use one over the other? Provide examples.

Frontend Engineer

MediumTechnical

2

267

Implement a debounce function

Write a debounce function that delays invoking a function until after a specified wait time has elapsed since the last time it was invoked.

Frontend Node.js

Senior Software Engineer

EasyPhone Screen

1

245

What is the virtual DOM and how does it work?

Explain the concept of virtual DOM in React. How does it improve performance compared to direct DOM manipulation?

Frontend Engineer

EasyPhone Screen

1

189

What is the difference between var, let, and const?

Explain the differences between var, let, and const in JavaScript. When would you use each one?

Frontend Node.js

Software Development Engineer

MediumTechnical

0

189

Implement React infinite scroll

Build an infinite scroll component in React that efficiently loads and displays large lists of items. Consider virtualization.

Frontend Engineer

EasyPhone Screen

1

167

Explain CSS specificity and how it works

What is CSS specificity? How does the browser determine which styles to apply when there are conflicting rules?

Frontend Engineer

MediumTechnical

1

212

What are React hooks rules and why do they exist?

Explain the rules of hooks in React. Why can't we call hooks inside loops, conditions, or nested functions?

Frontend Engineer

MediumTechnical

1

178

Implement a deep clone function in JavaScript

Write a function that creates a deep copy of a JavaScript object. Handle nested objects, arrays, and edge cases like circular references.

Frontend Node.js

Senior UI Engineer

EasyPhone Screen

1

245

Explain REST vs GraphQL

Compare REST and GraphQL APIs. What are the pros and cons of each approach? When would you choose one over the other?

Backend Frontend

Full Stack Engineer

MediumTechnical

1

189

What is memoization and when should you use it?

Explain the concept of memoization. Implement a memoize function and discuss when memoization is beneficial vs harmful.

Algorithms Frontend

Software Engineer

EasyPhone Screen

1

156

What is the difference between Promise.all and Promise.allSettled?

Explain the difference between Promise.all() and Promise.allSettled() in JavaScript. When would you use each?

Frontend Node.js

Frontend Developer

MediumTechnical

1

198

Implement throttle function

Write a throttle function that limits the rate at which a function can be called. It should invoke the function at most once per specified time period.

Frontend Node.js

Frontend Engineer

MediumTechnical

1

256

Implement Promise.all from scratch

Implement Promise.all in JavaScript without using the built-in method. Handle success and failure cases correctly.

Frontend Node.js

Software Engineer

EasyPhone Screen

1

234

What are the differences between cookies, localStorage, and sessionStorage?

Compare cookies, localStorage, and sessionStorage. What are the use cases, limitations, and security considerations for each?

Frontend Engineer