What is a namespace in Python?
A namespace is a mapping from names to objects, and scope decides which namespace Python checks first.
- Local, enclosing, global, builtins
- LEGB lookup rule
- Avoid name collisions
Quick recall
374 cards
What is list comprehension in Python?
List comprehensions build lists concisely from an iterable, often replacing small loops plus append calls.
- Compact loop expression
- Can include filter condition
- Readable only when kept simple
What is monkey patching?
Monkey patching replaces attributes at runtime, often for tests or temporary overrides.
- Changes behavior dynamically
- Useful in tests
- Can make code harder to reason about
What is the difference between is and == in Python?
`==` compares values, while `is` compares object identity.
- Equality vs same object
- Use is for None checks
- Interning can confuse beginners
API and network basics in JavaScript: fetch, XMLHttpRequest, HTTP methods, JSON responses, and error handling in API calls
Frontend and Node.js code often call APIs using `fetch` today, but interviews still expect you to know HTTP basics and sometimes older XHR patterns.
- Know common HTTP methods
- `fetch` returns a promise
- HTTP errors and network failures are not the same thing
Arithmetic, comparison, logical, ternary, nullish coalescing, optional chaining, and short-circuit operators
JavaScript operators cover math, comparisons, boolean logic, fallback values, safe property access, and concise branching.
- `??` differs from `||`
- Optional chaining stops on nullish access
- Short-circuiting affects evaluation
Asynchronous JavaScript: callbacks, callback hell, promises, promise states, promise chaining, async/await, try/catch with async, Promise.all, Promise.allSettled, Promise.race, and Promise.any
Modern async JavaScript is built on promises and `async`/`await`, but you still need to understand callbacks and promise coordination helpers.
- Promises are pending, fulfilled, or rejected
- `async` functions return promises
- Promise combinators solve different coordination problems
Browser storage in JavaScript: localStorage, sessionStorage, and cookies
Browsers offer several storage mechanisms with different persistence, size, and request-behavior trade-offs.
- `localStorage` persists across sessions
- `sessionStorage` lasts for the tab session
- Cookies can be sent with HTTP requests
Class syntax, constructor, instance methods, static methods, inheritance, super, encapsulation basics, and polymorphism basics in JavaScript
JavaScript classes provide cleaner syntax over prototype-based behavior, including constructors, instance methods, inheritance, and static members.
- `class` is syntax over prototypes
- `super` reaches parent behavior
- Encapsulation and polymorphism are design ideas, not just keywords
Closures, lexical scope, and practical uses of closures in JavaScript
A closure happens when an inner function keeps access to variables from its lexical outer scope even after the outer function returns.
- Scope is determined lexically
- Closures retain access to outer variables
- Useful for encapsulation and factories
Collections in JavaScript: Set, Map, WeakSet, and WeakMap
JavaScript has keyed and set-like collections beyond plain objects and arrays, including weak collections for object-keyed references.
- Map preserves insertion order and allows any key type
- Set stores unique values
- Weak collections hold weak references to objects only
Common JavaScript comparison topics for interviews
JavaScript interviews often use comparison questions to test whether you understand trade-offs, not just syntax.
- Comparisons reveal semantics and trade-offs
- Many pairs differ by mutation, coercion, or context
- Strong answers use short examples