React Component Development and State Management Quiz

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Questions and Answers

What does a React component return?

React elements

DOM elements

HTML elements

JSX elements (correct)

When importing React, what does it allow?

Allow JSX to be implemented in the function (correct)

Allow usage of jQuery

Allow CSS styling within the component

Allow direct DOM manipulation

What do props help us accomplish in React?

Make components more reusable (correct)

Create new React elements

Directly manipulate the DOM

Implement conditional rendering

What does the checked prop for multiple choice radios need to equal?

The value Signup and view all the answers

What does the [name] syntax represent in an object literal?

Dynamic keys Signup and view all the answers

What does the .map array method do in React?

Return a new array with transformed elements Signup and view all the answers

When does React gather all the data from a filled out form?

React handles the internal state of native DOM elements Signup and view all the answers

What does the button inside a form do?

Triggers the onSubmit handler of the form Signup and view all the answers

What does the fetch retrieve from an API?

Data from the API Signup and view all the answers

When does mounting and unmounting happen in a conditionally rendered component?

When the component is added or removed from the DOM Signup and view all the answers

What happens to the useEffect's cleanup function once the component is unmounted?

It is not unmounted and may cause memory leaks Signup and view all the answers

What does the useEffect hook's dependencies array determine?

When the useEffect will run by comparison Signup and view all the answers

What is a 'side effect' in React?

A code that is affected by an outside system Signup and view all the answers

What is the purpose of the dependencies array in the useEffect hook?

To specify when the useEffect will run Signup and view all the answers

When does React run the useEffect function?

First render assuming no dependencies; every re-render otherwise Signup and view all the answers

What is the essential prop needed for fetching props from an API?

key Signup and view all the answers

What is not unmounted once the component is unmounted, potentially causing a memory leak?

The event listeners added by the component Signup and view all the answers

Which of the following is not a valid mouse event in React?

drag Signup and view all the answers

What happens when a mouse is down on a button in React?

It appears pressed Signup and view all the answers

What type of parameters do event listeners receive in React?

Functions, defined before the return Signup and view all the answers

What do mouseenter and mouseleave events refer to in React?

Points move inside and outside an element Signup and view all the answers

Why is using states crucial in React?

For the UI to reflect the state of a list Signup and view all the answers

Before React, how was changing the DOM typically achieved?

By directly modifying the DOM elements Signup and view all the answers

What do useState and set provide to a React component?

Attributes, treating it like an object that changes based on those states Signup and view all the answers

What does React allow to automatically hook onto for adding new states?

State Signup and view all the answers

What is setState in React?

A method that takes an object as a parameter to describe the changes to the state Signup and view all the answers

What do props refer to in React?

Properties passed into a React component, with the restriction of being immutable Signup and view all the answers

What do states refer to in React?

Values managed by the component itself, similar to variables declared inside a function Signup and view all the answers

Which hook in React allows components to subscribe to a context?

useContext Signup and view all the answers

What is the use context in React primarily used for?

Sharing data that can be considered global for a tree of React components Signup and view all the answers

When using useContext in a functional component, what does it return?

The current context value for the context Signup and view all the answers

How can the children prop be utilized in a parent component?

By including {children} in its return statement Signup and view all the answers

In what way can the children prop be passed to a parent component?

Directly in between the opening and closing tags of the parent component Signup and view all the answers

What does the 'children' prop represent in the given example?

The elements passed into the Card component Signup and view all the answers

What is the purpose of the children prop in React?

To pass components as data to other components Signup and view all the answers

What is the main purpose of the Card component in the given example?

To wrap content in a div with styling Signup and view all the answers

What does the 'return {children};' statement inside the Card component indicate?

It returns the children passed into the Card component Signup and view all the answers

What are environment variables in Node.js?

External variables defined outside the application Signup and view all the answers

What is the primary function of environment variables in Node.js?

Allowing the app to behave differently based on the environment Signup and view all the answers

How are environment variables typically used in Node.js applications?

As external variables that can be brought into the application Signup and view all the answers

Where are environment variables typically stored in a Next.js project?

.env.local files Signup and view all the answers

What is the purpose of the .gitignore file in a Next.js project?

To ignore .env.local files when committing to Git Signup and view all the answers

How can environment variables prefixed with NEXT_PUBLIC_ be accessed in a Next.js code?

On both the server and the client Signup and view all the answers

Which type of environment variables are available on both the server and the client in a Next.js application?

Environment variables prefixed with NEXT_PUBLIC_ Signup and view all the answers

What is the main purpose of setting environment variables in the project settings in Vercel?

When deploying a Next.js app to Vercel Signup and view all the answers

How can you access environment variables stored in a .env.local file in Next.js code?

Using process.env Signup and view all the answers

What is the accessibility of environment variables without the NEXT_PUBLIC_ prefix in a Next.js application?

Only available on the server Signup and view all the answers

How are layouts defined in Next.js?

Using a special layout.js file Signup and view all the answers

What can utilizing layouts improve in a Next.js application?

Application efficiency by preserving state Signup and view all the answers

What is a benefit of nesting layouts in Next.js?

Creating more complex UI structures Signup and view all the answers

Study Notes

React Component Development and State Management

Essential prop needed for fetching props from an API is a key
Mouse events include enter, move, down, up, leave, over, out
Mouse down on a button makes it appear pressed
Mouseenter points move inside an element, while mouseleave points move outside an element
Parameters event listeners receive are functions, defined before the return
Using states in React is crucial for the UI to reflect the state of a list
Before React, changing the DOM involved appending the state of a list into the DOM tree
React allows automatically hooking onto a state for new states to be added
useState and set give the component attributes, treating it like an object that changes based on those states
setState is a method that takes an object as a parameter to describe the changes to the state
Props refer to properties passed into a React component, with the restriction of being immutable
State refers to values managed by the component itself, similar to variables declared inside a function

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-Authentication vs Authorization -JSON Web Tokens (JWTs) -{ children } prop -React Context -Custom Hooks -Environment Variables -layout.js