React Javascript

Question 1

Which command should be used to start a new React project?

Accepted Answer

npx create-react-app my-app

Answer

The command `npx create-react-app my-app` is the standard and recommended way to initiate a new React project. `npx` is a package runner that executes `create-react-app` without requiring a global installation, ensuring you always use the latest version. This command sets up a complete React development environment with all necessary configurations and boilerplate code.

Question 2

What does the command's reference to "my-app" mean?

npx create-react-app my-app

Accepted Answer

The title that you want to give your new app

Answer

In the command `npx create-react-app my-app`, 'my-app' is a placeholder for the desired name of your new React application. When executed, `create-react-app` will create a new directory with this specified name, containing all the initial files and configurations for your project. You should replace 'my-app' with a descriptive name for your application.

Question 3

Which command is used to launch the local development server for React?

Accepted Answer

npm start

Answer

After setting up a React project, the `npm start` command is used to launch the local development server. This command compiles your React application and opens it in your web browser, typically at `http://localhost:3000`. It also enables hot-reloading, which automatically updates the browser whenever you save changes to your code.

Question 4

What is the children prop?

Accepted Answer

A property that lets you set an object as a property

Answer

The `children` prop in React is a special property that allows components to receive and render content passed between their opening and closing tags. While its primary use is for component composition and nesting, the value of the `children` prop itself can be a JavaScript object, such as a React element object, an array of elements, or even a string. Therefore, it functions as a property that can hold an object representing the nested content.

Question 5

React components must start with a capital letter

Accepted Answer

True

Answer

In React, it is a strict convention and requirement for all custom component names to begin with a capital letter. This naming convention allows React to differentiate between user-defined components and standard HTML elements, which always start with a lowercase letter. Failing to capitalize a component name will cause React to misinterpret it as a regular HTML tag, leading to rendering errors.

React Practice Test

React Practice Test

React Javascript