| 1 | When is it a mistake to force a 'classic' design pattern into idiomatic JavaScript? JavaScript › Design Patterns in JavaScript | JavaScript | Design Patterns in JavaScript | Advanced |
| 2 | How is the Decorator pattern typically implemented in JavaScript? JavaScript › Design Patterns in JavaScript | JavaScript | Design Patterns in JavaScript | Intermediate |
| 3 | What is the Command pattern and where is it useful in JavaScript apps? JavaScript › Design Patterns in JavaScript | JavaScript | Design Patterns in JavaScript | Advanced |
| 4 | What is the Singleton pattern and how is it implemented in JavaScript? JavaScript › Design Patterns in JavaScript | JavaScript | Design Patterns in JavaScript | Beginner |
| 5 | How do you implement the Observer pattern in JavaScript? JavaScript › Design Patterns in JavaScript | JavaScript | Design Patterns in JavaScript | Intermediate |
| 6 | What is the Strategy pattern and how does it help avoid large if/else chains? JavaScript › Design Patterns in JavaScript | JavaScript | Design Patterns in JavaScript | Advanced |
| 7 | How do you implement the Proxy pattern using JavaScript's built-in Proxy object? JavaScript › Design Patterns in JavaScript | JavaScript | Design Patterns in JavaScript | Advanced |
| 8 | What is the Factory pattern, and how does it differ from calling a class constructor directly? JavaScript › Design Patterns in JavaScript | JavaScript | Design Patterns in JavaScript | Intermediate |
| 9 | What is the Adapter pattern and why is it useful when integrating third-party code? JavaScript › Design Patterns in JavaScript | JavaScript | Design Patterns in JavaScript | Advanced |
| 10 | What is the Module pattern and what problem does it solve? JavaScript › Design Patterns in JavaScript | JavaScript | Design Patterns in JavaScript | Beginner |
| 11 | What is Domain-Driven Design (DDD), and how do its concepts of entities, value objects, and aggregates apply to a Node.js codebase? Node.js › Architecture & Design Patterns | Node.js | Architecture & Design Patterns | Advanced |
| 12 | How is the Factory pattern commonly applied in Node.js applications, and what problem does it solve? Node.js › Architecture & Design Patterns | Node.js | Architecture & Design Patterns | Intermediate |
| 13 | What is the Singleton pattern, and what are the specific risks of using it in a Node.js application? Node.js › Architecture & Design Patterns | Node.js | Architecture & Design Patterns | Intermediate |
| 14 | What is Dependency Injection, and how is it typically implemented in Node.js given the language has no built-in DI container? Node.js › Architecture & Design Patterns | Node.js | Architecture & Design Patterns | Intermediate |
| 15 | What is the Strategy pattern, and how would you apply it to support multiple payment providers in a Node.js checkout service? Node.js › Architecture & Design Patterns | Node.js | Architecture & Design Patterns | Intermediate |
| 16 | What is a Facade pattern, and how might it be used to simplify a Node.js application's interaction with several third-party SDKs? Node.js › Architecture & Design Patterns | Node.js | Architecture & Design Patterns | Advanced |
| 17 | How does styled components let you write CSS directly inside your JavaScript files? React › Styling in React (CSS Modules, Styled Components & Tailwind) | React | Styling in React (CSS Modules, Styled Components & Tailwind) | Intermediate |
| 18 | What is error propagation, and how does an uncaught error in a nested function behave? JavaScript › Error Handling | JavaScript | Error Handling | Intermediate |
| 19 | What is snapshot testing and what's a common pitfall with it? JavaScript › Debugging, Testing & Tooling | JavaScript | Debugging, Testing & Tooling | Advanced |
| 20 | Why is BigInt generally the wrong tool for representing monetary amounts with decimals, like $19.99? JavaScript › Numbers, Math & BigInt | JavaScript | Numbers, Math & BigInt | Advanced |
| 21 | How does method overriding with super work in JavaScript classes? JavaScript › Classes & Class Syntax | JavaScript | Classes & Class Syntax | Advanced |
| 22 | How would you build an interactive CLI wizard that prompts the user for multiple pieces of input using a library like Inquirer.js? Node.js › CLI Tools & Scripting with Node.js | Node.js | CLI Tools & Scripting with Node.js | Advanced |
| 23 | What does the node:util.types module provide, and how does it differ from JavaScript's built-in typeof operator? Node.js › Core Node.js Modules | Node.js | Core Node.js Modules | Intermediate |
| 24 | How do you format a date for a specific locale without a library? JavaScript › Date, Time & Internationalization (Intl API) | JavaScript | Date, Time & Internationalization (Intl API) | Intermediate |
| 25 | How do you handle out-of-range writes to a TypedArray safely? JavaScript › ArrayBuffer, TypedArrays & Binary Data | JavaScript | ArrayBuffer, TypedArrays & Binary Data | Advanced |
| 26 | What is the Temporal API and what problem does it solve? JavaScript › Date, Time & Internationalization (Intl API) | JavaScript | Date, Time & Internationalization (Intl API) | Advanced |
| 27 | What is event bubbling? JavaScript › DOM & Events | JavaScript | DOM & Events | Beginner |
| 28 | What is IndexedDB and how does it differ from a simple key-value store? JavaScript › Browser Storage & Web APIs | JavaScript | Browser Storage & Web APIs | Intermediate |
| 29 | How do you delegate from one generator to another using yield*? JavaScript › Iterators & Generators | JavaScript | Iterators & Generators | Intermediate |
| 30 | How does sort() compare values by default, and how do you fix numeric sorting? JavaScript › Arrays & Array Methods | JavaScript | Arrays & Array Methods | Advanced |
| 31 | What's the difference between the capturing and bubbling phases of event propagation? JavaScript › DOM & Events | JavaScript | DOM & Events | Advanced |
| 32 | How does mark-and-sweep garbage collection actually determine which objects are reachable? JavaScript › Memory Management & Garbage Collection | JavaScript | Memory Management & Garbage Collection | Advanced |
| 33 | What does the node:events module's EventEmitter class provide, and what naming convention do most Node.js core APIs follow when using it? Node.js › Core Node.js Modules | Node.js | Core Node.js Modules | Beginner |
| 34 | How do you create a custom class that emits events by extending Node's built-in EventEmitter? Node.js › Events & EventEmitter | Node.js | Events & EventEmitter | Beginner |
| 35 | How would you implement Attribute-Based Access Control (ABAC) in a Node.js application when RBAC roles aren't expressive enough? Node.js › Authentication & Authorization | Node.js | Authentication & Authorization | Intermediate |
| 36 | How does Sequelize define models and relationships for a relational (SQL) database in Node.js? Node.js › Databases & ORMs (MongoDB/Mongoose, SQL/Sequelize) | Node.js | Databases & ORMs (MongoDB/Mongoose, SQL/Sequelize) | Intermediate |
| 37 | Why can decorators make code harder to statically analyze or tree-shake, and what's a common criticism of overusing them? TypeScript › Decorators | TypeScript | Decorators | Advanced |
| 38 | How would you implement a custom event that carries multiple pieces of data, and what's the convention for structuring the emitted payload? Node.js › Events & EventEmitter | Node.js | Events & EventEmitter | Advanced |
| 39 | What's the difference between a named export and a default export? JavaScript › ES Modules | JavaScript | ES Modules | Beginner |
| 40 | What does the # syntax mean for class members? JavaScript › Classes & Class Syntax | JavaScript | Classes & Class Syntax | Intermediate |
| 41 | What's the difference between event.target and event.currentTarget? JavaScript › DOM & Events | JavaScript | DOM & Events | Intermediate |
| 42 | How do you create and dispatch a custom DOM event? JavaScript › DOM & Events | JavaScript | DOM & Events | Intermediate |
| 43 | How does MutationObserver let you react to DOM changes made by other code? JavaScript › DOM & Events | JavaScript | DOM & Events | Advanced |
| 44 | Why can circular module imports (Module A imports B, which imports A) cause subtle bugs? JavaScript › ES Modules | JavaScript | ES Modules | Advanced |
| 45 | How would you implement a custom Symbol.iterator for a tree data structure to enable depth-first traversal with for...of? JavaScript › Iterators & Generators | JavaScript | Iterators & Generators | Advanced |
| 46 | How would you use a Map to implement an LRU (Least Recently Used) cache? JavaScript › Map, Set, WeakMap & WeakSet | JavaScript | Map, Set, WeakMap & WeakSet | Advanced |
| 47 | What is optimistic concurrency control, and how would you implement it to prevent lost updates when two users edit the same record simultaneously? Node.js › Databases | Node.js | Databases | Advanced |