EPAM Systems Senior Javascript Developer interview questions

Event loop SOLID principles Currying - sum(1)(2)() - implementation Const Person = { Name Age setName() => arrow setAge: function() } console(Person.name) console(Person.age) Websocket, Polling requestAnimationFrame() RBAC, theme - context or store Union, intersection Git rebase, merge Partial, omit Testing library - jest, rtl Directives, composition Using ref - change button color useHistory - maintain prev and next array.map(a => a < 3) React fiber Prioritisation in react - how does it happen ssr, nextjs Liskov, IoC Code review Performance optimization - initial load 10s Garbage collection Memory optimization Critical rendering path when you use custom hook how would you maintain reference when its used across multiple components, something to do with useEffect Proto and prototypal inheritance Lifecycle hooks React versions Owasp top 10 Cors Xss How react handles xss V8 engine - implementation

One thing that stood out was the unexpected range of topics covered during the interview. While the role was for a Senior JavaScript Developer position, the interview went beyond just JavaScript and React, covering HTML, CSS, databases, AWS, and even backend technologies. One of the more surprising parts was that they had two exercises focused purely on JavaScript, which I answered correctly. Despite feeling confident about my answers and the positive feedback from the interviewers, I was shocked to learn later that I wasn’t selected for the role.