React Introduction Quiz

Question 1

What kind of tool is React?

Accepted Answer

A JavaScript library for building user interfaces

Answer

A complete web framework with built-in routing and data fetching

Answer

A CSS framework for styling pages

Answer

A database query language

Question 2

What does it mean that React is declarative?

Accepted Answer

You describe what the UI should look like for the current data and React works out the updates

Answer

You write the exact DOM steps needed to update the page

Answer

You declare all variables before using them

Answer

You must declare every component in a central registry

Question 3

What does a piece of JSX actually produce when it runs?

Accepted Answer

A plain JavaScript object describing the intended UI

Answer

A real DOM node inserted into the page

Answer

An HTML string that is parsed later

Answer

A CSS rule

Question 4

When a component's state changes, what does React do with the component function?

Accepted Answer

It calls the whole component function again and diffs the result

Answer

It patches only the changed line of the function

Answer

It never calls the function again after the first render

Answer

It reloads the page

Question 5

Why must a component name start with a capital letter?

Accepted Answer

JSX treats lowercase tags as HTML elements and capitalised tags as components

Answer

It is only a style convention with no effect

Answer

React refuses to compile lowercase functions

Answer

Lowercase names are reserved for hooks