Tradeoff Stories and the Design They Led To
A 5-question set where each behavioral tradeoff story is paired with the design choice it forced. Drawn from a senior backend loop where the interviewer kept pushing past the story into the code that proved it.
Question Bundle
JavaScript
interview-prep
behavioral-interview
system-design-interview
backend
By @emmakim
April 15, 2026
·
Updated May 18, 2026
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The interviewer asked: "Tell me about a tradeoff you owned where you picked the worse option on paper." Follow-up: "Show me the cache you ended up writing instead." Sketch the read-through cache I drew.
What I ended up shipping
I traced one hit and one miss:
JavaScript
await getUser('u-1'); // miss: DB hit, cache stores result, returns user
await getUser('u-1'); // hit: cache returns user, no DB call
await getUser('u-2'); // miss: DB hit, cache stores result, returns user4 more questions and all solutions are locked.
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