## Round 1 - Coding (Frontend/JS) ## Problem Implement a `memo` function that wraps any pure function and caches its results. The cache key should be derived from the serialized arguments. Support an optional `maxSize` to limit cache entries (evict least-recently-used when full). ```javascript function memo(fn, { maxSize = Infinity } = {}) { // Your implementation } // Usage const expensiveAdd = memo((a, b) => { console.log('computing'); return a + b; }, { maxSize: 3 }); ``` ``` expensiveAdd(1, 2) -> 3 // logs "computing" expensiveAdd(1, 2) -> 3 // cache hit, no log expensiveAdd(2, 3) -> 5 // logs "computing" expensiveAdd(1, 2) -> 3 // still cached // With maxSize=2: memo(fn, {maxSize:2}) fn(1) fn(2) fn(3) // fn(1) evicted; fn(3) miss -> recomputes ``` ## Follow-ups 1. Your key serialization uses `JSON.stringify`. What breaks for functions, circular refs, or `undefined` args? How do you fix it? 2. Add a `maxAge` option (in ms) after which a cache entry is considered stale. 3. How would you make this work for async functions that return Promises, avoiding thundering-herd on concurrent calls with the same args? 4. Where in a React component tree would you apply memoization, and how does `useMemo` differ from this implementation?

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Memo Function: Implement a Generic Memoization Wrapper in JavaScript

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Round 1 - Coding (Frontend/JS) Problem Implement a memo function that wraps any pure function and caches its results. The cache key should be derived from the serialized arguments. Support an optional maxSize to limit cache entries (evict least-recently-used when full). Follow-ups Your key serialization uses JSON.stringify. What breaks for functions, circular refs, or undefined args? How do you fix it? Add a maxAge option (in ms) after which a cache entry is considered stale. How would you make…

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This is a candidate experience report from a confluent interview during the phone round.

It covers the following topics: Coding, Phone, Frontend, Dynamic Programming .

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Memo Function: Implement a Generic Memoization Wrapper in JavaScript

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