JavaScript Utility Implementations and Standard Polyfills
Machine coding rounds and live technical screens routinely require implementing utility functions from scratch without third-party libraries like Lodash. Interviewers evaluate how you handle edge cases, preserve execution contexts (`this`), forward arguments, and avoid memory leaks.
Step through production-grade implementations of debounce with leading/trailing options, throttle, recursive deep cloning, currying, and Promise combinators. Each utility includes thorough unit tests covering realistic edge cases.
Interview Modules (10)
1. Debounce and Throttle Implementations
Interactive ReadyWhat is logged to the console when the following code executes, and how do debounce cancellation and leading-e...
2. Flattening Nested Arrays
Interactive ReadyWhat is logged to the console when Array.prototype.flat() is executed on deeply nested and sparse arrays, and ...
3. Memoize & Cache Layer
Interactive ReadyWhat is logged to the console when the following memoized functions are invoked, and how do default JSON argum...
4. Higher-Order Functions & Currying
Interactive ReadyWhat is logged to the console when the following code executes, and how does the execution order differ betwee...
5. JavaScript Array Methods
Interactive ReadyWhat is logged to the console when the following JavaScript code executes, and how do missing return statement...
6. Event Emitter & Observer
Interactive ReadyWhat is logged to the console when multiple listeners are registered, removed dynamically during dispatch, and...
7. Deep Clone with Circular References
Interactive ReadyWhat is logged to the console when the following deepClone implementation executes on an object containing cir...
8. Promise Polyfill (Promises/A+ Spec)
Interactive ReadyWhat is logged to the console when the following educational MyPromise implementation executes with chaining, ...
9. Custom bind, call and apply
Interactive ReadyWhat is logged to the console when custom implementations of call, apply, and bind execute with argument forwa...
10. Retry with Exponential Backoff & Jitter
Interactive ReadyWhat is logged to the console when the following retry utility executes against an API that fails twice with 5...