React Basics Quiz

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Question 1/15

How can you share logic between two React components?

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Question 2/15

What is JSX in React?

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Question 3/15

Which method is used to update state in a class component?

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Question 4/15

Which of these statements about state in React is true?

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Question 5/15

Which method should be overridden to return a React element from a class component?

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Question 6/15

What does the 'return' statement do in a React component?
function Greeting() {
  return <h1>Hello, world!</h1>;
}

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Question 7/15

In React, how do you conditionally render elements based on state?
class Example extends React.Component {
  state = { show: true };

  render() {
    return (
      <div>
        {this.state.show ? <p>Displayed</p> : <p>Hidden</p>}
      </div>
    );
  }
}

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Question 8/15

How can you pass data from a parent to a child component in React?

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Question 9/15

What happens when you call setState() in React?

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Question 10/15

What is the significance of 'props' in React?

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Question 11/15

How do you handle events in React?

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Question 12/15

What is the purpose of keys in React lists?

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Question 13/15

Which statement about 'useState' hook is true?

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Question 14/15

When should you use React's StrictMode?

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Question 15/15

What is the purpose of componentDidMount lifecycle method?

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Your Answers

Question 1/15
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How can you share logic between two React components?

Available answers

In React, logic that needs to be shared between components can be encapsulated in custom hooks. These hooks house reusable logic that function components can utilize, promoting cleaner and more maintainable code.
Question 2/15
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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 3/15
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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 4/15
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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 5/15
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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 6/15
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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 7/15
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In React, how do you conditionally render elements based on state?
class Example extends React.Component {
  state = { show: true };

  render() {
    return (
      <div>
        {this.state.show ? <p>Displayed</p> : <p>Hidden</p>}
      </div>
    );
  }
}

Available answers

In React, you can use JavaScript's built-in conditional operators within JSX to control what gets rendered, such as '&&' for logical AND and '?' for ternary conditions. This enables you to create dynamic interfaces conveniently:
this.state.show ? <p>Displayed</p> : <p>Hidden</p>
.
Question 8/15
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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.
Question 9/15
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What happens when you call setState() in React?

Available answers

When
setState()
is called in a React component, it schedules an update to the component's state. The component will re-render, reflecting the change in state and thus redrawing the UI to match the new data.
Question 10/15
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What is the significance of 'props' in React?

Available answers

Props (short for properties) are inputs to a component typically passed from a parent component. They are used to pass data and event handlers from a parent to a child component. Props are immutable, meaning a component should not change them.
Question 11/15
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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 12/15
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What is the purpose of keys in React lists?

Available answers

In React, keys help identify which items have changed, been added, or been removed. Keys should be given to the elements inside the array to give the elements a stable identity:
const items = items.map((item) => <li key={item.id}>{item.name}</li>)
.
Question 13/15
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Which statement about 'useState' hook is true?

Available answers

The 'useState' hook lets you add state to function components. It returns an array containing the current state and a function to update that state, allowing functional components to manage state without converting them to class components.
Question 14/15
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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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What is the purpose of componentDidMount lifecycle method?

Available answers

The 'componentDidMount' method is invoked immediately after a component is mounted. This is the best place to initiate network requests, set timers, or directly interact with the DOM.