What design patterns do you use (DRY, SOLID, GRASP, etc.)?
Middle
226
Frontend
6413
681
What are the differences between useEffect and useLayoutEffect hooks?
Middle
217
What new features appeared in React 19? Tell us about Concurrent Mode and startTransition.
Middle
200
What methods of working with context (this) exist? What is the signature of the call method? How does call differ from apply?
Middle
197
In what cases does a component re-render in React?
Middle
182
What does the typeof operator return for null?
Middle
178
What are the phases of browser events (bubbling and capturing)? How to stop bubbling? How to prevent default action?
Middle
177
What is the purpose of the OPTIONS method? When is it sent automatically?
Middle
173
What HTTP headers are important for frontend developers in terms of performance optimization (e.g., caching)?
Middle
170
How do you react to code with O(n²) complexity during code review?
Middle
163
What is the signature of the reduce method on arrays? What should be returned from the callback on each iteration?
Middle
163
Why did you decide to use an iFrame for the preview mode?
Middle
159
Tell me about Promise: states, static methods (all, any, allSettled, race). What does Promise.all return if one of the promises fails?
Middle
155
TypeScript task: Is the call to the getUsername function with an object of type IUser (a custom consumer interface) correct if the field structure matches TUser from the library? Explain the principle of structural typing.
Middle
155
What are the ways to declare functions in JavaScript? How does function declaration differ from function expression? How does arrow function differ from function declaration?
Middle
154
Tell about CORS: what is it for, what headers are used?
Middle
152
Have you ever used the 'any' type in TypeScript? What can replace it?
Middle
151
What is the use of the useRef hook?
Middle
150
Does CSS block page rendering?
Middle
150
Is there code review in your project? What standards and requirements are used for the code?
Middle
148