How would you use bitwise operators to implement a simple permissions/flags system?

Explain how 'this' binding works across the four invocation patterns in JavaScript (regular function, method, constructor, arrow function).

How does V8's hidden class and inline caching optimization affect how you should write JavaScript objects?

What is structural sharing and why does it matter when working with deep copies and state management?

Explain how floating-point representation can cause subtle bugs in real applications, and how do you mitigate them?

How would you debug a memory leak caused by closures retaining references in a large JavaScript application?

What is the difference between primitive wrapper objects and primitive values in JavaScript, and when does autoboxing occur?

How does the abstract equality (==) algorithm actually work step-by-step in the ECMAScript specification?

What are the differences between the engine's call stack, heap, and event loop in relation to JavaScript's execution model?

Explain Symbol's role in JavaScript and a real-world scenario where it solves a problem other types can't.

What is a labeled `break` statement and when would you use it?

Explain the nullish coalescing operator `??` and how it differs from `||` for default values.

What is optional chaining `?.` and how does it relate to conditional control flow?

How would you refactor a long `switch` statement using an object lookup table? When is this pattern better?

How does `switch` differ from `if...else if` in terms of performance and use case?

What is the 'early return' pattern and how does it improve control flow readability?

Scenario: You're reviewing a colleague's code and see `if (value == null)` — is this a bug or intentional? Explain.

Scenario: Write a function to find the first duplicate in an array using a loop. Optimize from O(n²) to O(n).

What is 'callback hell' and what techniques can you use to avoid it?

What is a higher-order function? Name some built-in JavaScript higher-order functions.