PwC — MERN Stack

Short answers only · ShopNest-style examples · 12 questions

.NET MERN MEAN AI Cloud SDE-1 SDE-2 SDE-3 L1 L2 L3

1 What is the Virtual DOM in React? Mid 2 Explain useState and useEffect with a real example. Mid 3 What is middleware in Express? Mid 4 Explain the Node.js event loop simply. Mid 5 MongoDB vs SQL — when do you pick each? Mid 6 How do you secure a MERN API? Mid 7 How do you fix unnecessary React re-renders? Mid 8 What is Redux vs Context? Mid 9 How would you debug a Node app that works locally but fails in Docker? Mid 10 Explain REST status codes you use daily. Mid 11 Controlled vs uncontrolled inputs in React? Mid 12 How do you handle CORS with Express and React? Mid

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