Front End Developer Interview Questions

12,571 front end developer interview questions shared by candidates

promises, event loop in depth, tricky output based questions (not common, really tests). Your experience based, polyfills to write, code block to fix,HLD, LLD is scenario to break down into comp, data models, HM is experience and challenges and fitment discussion
avatar

Software Engineer - Front End

Interviewed at Wayground

3.5
Oct 3, 2023

promises, event loop in depth, tricky output based questions (not common, really tests). Your experience based, polyfills to write, code block to fix,HLD, LLD is scenario to break down into comp, data models, HM is experience and challenges and fitment discussion

1. If I start a startup would I prefer writing unstructured code in two month or clean, efficient, testable code in a year. (Comparing 2 vs 12 months is a totally unrealistic example. Experienced developer would add new features faster when she/he has clean and well designed code base. There will be fewer bugs also. A good code base would never take 6 times longer to develop.) 2. Would I spend time to add a feature to Web app or to migrate it to ES6? 3. Why do some of TransferWise users drop off at the fourth transfer flow process, which is entering billing information? 4. What would I change to make more users to enter their billing information? 5. How would I know that my change improved the statistics if there were 10 more changes?
avatar

Front-end Web Developer

Interviewed at Wise

3.7
Sep 14, 2015

1. If I start a startup would I prefer writing unstructured code in two month or clean, efficient, testable code in a year. (Comparing 2 vs 12 months is a totally unrealistic example. Experienced developer would add new features faster when she/he has clean and well designed code base. There will be fewer bugs also. A good code base would never take 6 times longer to develop.) 2. Would I spend time to add a feature to Web app or to migrate it to ES6? 3. Why do some of TransferWise users drop off at the fourth transfer flow process, which is entering billing information? 4. What would I change to make more users to enter their billing information? 5. How would I know that my change improved the statistics if there were 10 more changes?

Serialise IDs from a nested tree of items
 const data = [
  { id: 1, items: [{ id: 4, items: [{id: 5}, {id: 6, items: [{id: 8}]}]}]},
  { id: 2, items: [{ id: 7}]},
  { id: 3 },
  { id: 9, items: [{id: 10, items: [{id: 12}]}, {id: 11}] }
];

// Should return [1, 2, 3, 9, 4, 7, 10, 11, 5, 6, 12, 8] 
avatar

Senior Front End Developer

Interviewed at Apple

4.1
Nov 10, 2017

Serialise IDs from a nested tree of items
 const data = [
  { id: 1, items: [{ id: 4, items: [{id: 5}, {id: 6, items: [{id: 8}]}]}]},
  { id: 2, items: [{ id: 7}]},
  { id: 3 },
  { id: 9, items: [{id: 10, items: [{id: 12}]}, {id: 11}] }
];

// Should return [1, 2, 3, 9, 4, 7, 10, 11, 5, 6, 12, 8] 

Viewing 591 - 600 interview questions

Glassdoor has 12,571 interview questions and reports from Front end developer interviews. Prepare for your interview. Get hired. Love your job.