Interview prep

Question 1

What and why React?

Answer 1

Effecient DOM updates for interactions
Component based mental models
Declarative structure JSX
Large ecosystem
Beyond SPA - SSR for SEO and Loading performance; Streaming
beyond the web to mobile and desktop

Question 2

How is React efficient?

Answer 2

Fiber Architecture
Virtual DOM vs Real DOM, diffiing
Batch updates - batching

Question 3

How can you stop automatic batching?

Answer 3

flushSync API to immediately push updated to DOM

Question 4

What is HOC?

Answer 4

cross cutting cocerns
decorate component with props or statful logic
Its a pattern not a React thing

Question 5

What is pure component?

Answer 5

same input same output

Question 6

What is props?

Answer 6

immutable data that is passed into a component
- use for components to communicate within the component tree
- parent to child communication.
- child-to-parent communication via callbacks props
- descendants communication if no context

Question 7

What is state?

Answer 7

• a component’s local data that if fully controlled by the component
• triggers re-render/reconciliation

Question 8

How do update a nested object state?

Answer 8

spread each nesting in the React’s setter
Immner for third party approach