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Full Stack Interview Questions
JavaScript, React, networking and databases — the rounds that gate every web role.
4 of 4 questions
Topic
Difficulty
Frequency
Round
Type
BeginnerAsked very oftenBrowserPhone screen · Concept
What happens when you type a URL and press Enter?
The classic warm-up question that secretly tests how deep your mental model of the web goes.
dnstlshttp
IntermediateAsked very oftenReactCoding round · Debugging
Why does my useEffect run twice in Strict Mode?
Your effect fires twice in development and once in production — the right answer is cleanup, not removing StrictMode.
reactuseeffectstrict-mode
IntermediateAsked very oftenJavaScriptCoding round · Coding
What does this event-loop snippet print?
A four-line snippet that separates people who memorized "microtasks before macrotasks" from those who can run the queues in their head.
javascriptevent-loopmicrotasks
IntermediateAsked sometimesDatabasesConcept round · Concept
How do database indexes work, and when do they hurt?
A B+Tree is a tiny table of contents that turns a million-row scan into a handful of page reads — until writes and row lookups tip the balance.
databasesindexesb-tree