React Basics Quiz
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Question 1/15
What is JSX in React?
Select your answer
Question 2/15
How do you create a class-based component in React?
class MyComponent extends React.Component {
render() {
return <div>Hello World</div>;
}
}
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Question 3/15
Which of these statements about state in React is true?
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Question 4/15
How does React update the user interface efficiently?
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Question 5/15
How can you bind functions to the correct context in React class components?
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Question 6/15
What is a React component?
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Question 7/15
How do you write comments in JSX?
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Question 8/15
What does the 'return' statement do in a React component?
function Greeting() {
return <h1>Hello, world!</h1>;
}
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Question 9/15
Which method should be overridden to return a React element from a class component?
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Question 10/15
How do you handle events in React?
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Question 11/15
Can React handle asynchronous operations within components?
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Question 12/15
Which method is used to update state in a class component?
Select your answer
Question 13/15
How do you declare a functional component in React?
function MyComponent() {
return <div>Hello World</div>;
}
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Question 14/15
When should you use React's StrictMode?
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Question 15/15
How can you pass data from a parent to a child component in React?
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Your Answers
Question 1/15
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answer was correct
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answer was incorrect
What is JSX in React?
Available answers
JSX is a syntax extension for JavaScript that resembles XML or HTML. It is used within React to describe what the UI should look like. Rather than separating logic and presentation as in some traditional approaches, JSX integrates HTML with JavaScript code, making it easier to visualize the structure of the UI.
Question 2/15
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answer was correct
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answer was incorrect
How do you create a class-based component in React?
class MyComponent extends React.Component {
render() {
return <div>Hello World</div>;
}
}
Available answers
To create a class-based component in React, you use the 'class' keyword to define a new class that extends 'React.Component'. This class must include a 'render()' method that returns a React element.
Question 3/15
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answer was correct
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answer was incorrect
Which of these statements about state in React is true?
Available answers
State in React is used to store dynamic data that may change over time and influence the output of a component's render function. Contrary to props, which are passed into a component, state is local to the component and managed entirely within it.
Question 4/15
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answer was correct
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answer was incorrect
How does React update the user interface efficiently?
Available answers
React efficiently updates the user interface by using a virtual DOM. When changes occur, React creates a virtual DOM and calculates the differences between the new and previous versions. React then updates only the parts of the real DOM that changed, improving performance and reducing unnecessary updates.
Question 5/15
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answer was correct
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answer was incorrect
How can you bind functions to the correct context in React class components?
Available answers
In React class components, you can ensure methods have the correct context using arrow functions (since they don't create a 'this' context) or explicitly binding them using the
bind()
method inside the constructor.
Question 6/15
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answer was correct
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answer was incorrect
What is a React component?
Available answers
In React, a component is a JavaScript function or class that optionally accepts inputs (known as 'props') and returns a React element that describes how a section of the UI should appear. Components can be either stateful or stateless, and they can be composed within other components.
Question 7/15
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answer was correct
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How do you write comments in JSX?
Available answers
In JSX, you write comments using curly braces and '/* *'/ syntax. This allows for comments to be embedded within JSX code:
{/* Your comment here */}
. Regular JavaScript comments outside JSX work the same as usual.
Question 8/15
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answer was correct
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answer was incorrect
What does the 'return' statement do in a React component?
function Greeting() {
return <h1>Hello, world!</h1>;
}
Available answers
In a React component, the 'return' statement declares what JSX, or combination of React elements, should be displayed in the UI. This forms the basis of how the component renders itself to the DOM.
Question 9/15
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answer was correct
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answer was incorrect
Which method should be overridden to return a React element from a class component?
Available answers
The
render()
method is required for class components and should be overridden to return the React elements dictating what gets rendered to the DOM. The elements in the render()
method directly represent the rendered interface.
Question 10/15
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answer was correct
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answer was incorrect
How do you handle events in React?
Available answers
In React, events are handled using camelCase syntax. Instead of using HTML attributes like 'onclick', you pass a function as the event handler in JSX:
<button onClick={handleClick}>Click Me</button>
.
Question 11/15
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answer was correct
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answer was incorrect
Can React handle asynchronous operations within components?
Available answers
React can handle asynchronous operations such as API calls and timers within components. You can use lifecycle methods like 'componentDidMount' in class components or 'useEffect' hooks in function components to perform these operations.
Question 12/15
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answer was correct
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answer was incorrect
Which method is used to update state in a class component?
Available answers
In class components, you should use the 'setState()' method to update the component's state. This method ensures the component is re-rendered with the updated state and handles updating the state asynchronously.
Question 13/15
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answer was correct
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answer was incorrect
How do you declare a functional component in React?
function MyComponent() {
return <div>Hello World</div>;
}
Available answers
In React, you can declare a functional component by defining a JavaScript function that returns a JSX element. This function receives 'props' as an argument and returns the UI representation.
Question 14/15
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answer was correct
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answer was incorrect
When should you use React's StrictMode?
Available answers
<React.StrictMode>
is used for highlighting potential problems in a React application. Enclosing the application in <React.StrictMode>
helps developers identify unsafe lifecycles, legacy API usage, and multiple driver side effects.
Question 15/15
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answer was correct
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answer was incorrect
How can you pass data from a parent to a child component in React?
Available answers
To pass data from a parent to a child component in React, props are used. You can pass String, Object, Array, and Function in the props.