GeeksSmith
Understand. Visualize. Practice. Crack the Interview. Master JavaScript, React Fiber, Next.js, Performance, and Frontend System Design for Senior, Lead, and Staff roles.
Your Interview Readiness
54 Deep Modules
6 Days
7 Live Sandboxes
Walmart · ConveGenius · Amazon
Company-Specific Fast Tracks
View All Tracks →Tekion Corp Track
Pinterest-like Masonry Grid HLD, Reflow/Repaint GPU animations, and Async Task Schedulers.
ConveGenius Track
Frontend Engineering Lead: WCAG 2.1 AA, AI Token Streaming & Low-Bandwidth Optimizations.
Walmart Global Tech
100k Virtualized Tables, React Fiber work loops, and memory leak profiling.
Amazon FEE Track
Edge Caching, Micro-frontends, LRU cache polyfills, and Leadership Principles.
Featured Learning Modules
View All 54 Topics →Closures
A closure is a function bundled together with the lexical scope it was created in, so it keeps access to those outer variables even after the outer function has returned.
Event Loop & Asynchronous JavaScript
The Event Loop is the single-threaded coordinator that constantly monitors the Call Stack and transfers pending callbacks from the Microtask Queue and Task Queue once the stack is empty.
Promises, Async/Await & Race Conditions
A Promise is an object representing the eventual completion (or failure) of an asynchronous operation and its resulting value, preventing callback hell via chainable state transitions (pending -> fulfilled/rejected).
Debounce & Throttle Internals
Debounce delays execution until a burst of events pauses for N milliseconds; Throttle guarantees execution at most once every N milliseconds during continuous event streams.
Object Mutation & Deep Clone Internals
Deep Cloning creates an exact, independent copy of an object and all its nested references, avoiding shared object mutations while handling complex types like Date, RegExp, Map, Set, and circular references.
JavaScript & React Memory Leaks
A memory leak occurs when memory allocated by an application is no longer needed by the program logic but is retained by unintended references, preventing Garbage Collection (GC) from reclaiming it.