Frameworks Flashcards

What is the role of `forwardRef` in React?

Answer: Allows a parent component to access a child component's DOM node or instance via a ref

forwardRef lets a component pass a ref it receives down to a DOM element or another component, enabling parent components to interact with child DOM nodes.

In Vue 3, what is the key difference between `ref()` and `reactive()`?

Answer: ref() wraps any value and accesses it via .value; reactive() makes a plain object deeply reactive

ref() wraps any value type and requires .value access in JavaScript, while reactive() takes a plain object and makes all its properties reactive without .value.

What is Angular's change detection strategy `OnPush` used for?

Answer: Limits change detection to run only when input references change or events fire within the component

OnPush tells Angular to skip change detection for a component subtree unless an input reference changes, an event originates within it, or it's manually marked for check.

Which Express.js method correctly handles errors passed via `next(err)`?

Answer: An error-handling middleware with signature (err, req, res, next)

Express identifies error-handling middleware by its four-parameter signature (err, req, res, next); the extra `err` parameter distinguishes it from regular middleware.

What is hydration in the context of server-side rendered React applications?

Answer: The process of attaching React event listeners to server-rendered HTML already in the DOM

Hydration is when React takes over static HTML rendered by the server, attaches event listeners, and makes the page fully interactive without re-rendering the DOM.

In Django REST Framework, what is a Serializer used for?

Answer: Converting complex data types like querysets to native Python datatypes and validating input

DRF Serializers handle converting Django model instances or querysets to JSON-compatible data and validating incoming request data against defined fields.

What does the `key` prop do when rendering lists in React?

Answer: Helps React identify which items changed, added, or removed for efficient DOM updates

Keys give React a stable identity for each list element, allowing it to reconcile the virtual DOM efficiently and avoid unnecessary re-renders or DOM mutations.