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Lessons (10)

• Two Pointers & Sliding Window

  … recompute every window → O(n × k) // ✅ Slide: add the new element, subtract the old one → O(n) function …

• SQL Interview Query Drills

  … For an average per class, use a correlated subquery or partitioned window function. Q26: Third-highest distinct salary …

• DSA Interview Patterns Cheat Sheet

  … intervals (merge overlapping meetings) js function mergeIntervals(intervals) { const sorted = intervals.toSorted((a, b) = a[0] - b[0 …

• React Hooks in Practice

  … never inside if , loops or nested functions. 2. Only call hooks from React functions (components or custom hooks …

• Stacks & Queues

  … When a function returns, its frame is popped. js function a() { b(); } function b() { c(); } function c() { console …

• JavaScript Essentials: Event Loop, Closures & this

  … Q -- "plain fn()" P["this = undefined (strict) / window"] Q -- arrow function A["this = inherited from the surrounding code …

• State Management (Redux, Zustand, TanStack Query)

  … Don't hand-roll that with useEffect + useState . jsx import { useQuery, useMutation, useQueryClient } from "@tanstack/react-query"; function …

• MVC, MVP & MVVM

  … all the state and logic, no JSX function useLoginViewModel() { const [email, setEmail] = useState(""); const [password, setPassword] = useState(""); const …

• Frontend Performance & Core Web Vitals

  … render only the ~20 visible rows (TanStack Virtual, react-window) Context updates re-render everything Split contexts, or …

• Caching & Redis

  … SET product:42 (expires in 300 s) end js async function getProduct(id) { const key = product:${id} ; const …