Computer Knowledge

GUI and Web Frameworks

1,711 Questions

Graphical user interface and web frameworks involve layout management, directives, and application design across platforms like Android and Angular. These concepts are tested in computer science and IT officer competitive exams. Review these questions to understand UI components and coding standards.

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GUI and Web Frameworks Questions

Multiple choice

How do you stop the propagation of an event in React?

  1. Using the preventDefault() method

  2. Using the stopPropagation() method

  3. Using the cancelBubble property

  4. Using the return false statement
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The stopPropagation() method is used to stop the propagation of an event in React. It prevents the event from bubbling up to the parent elements.

Multiple choice

How do you add an event listener to an element in React?

  1. Using the addEventListener() method

  2. Using the onClick() event handler

  3. Using the onEvent() method

  4. Using the handleEvent() method
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The addEventListener() method is used to add an event listener to an element in React. It is the most common way to add an event listener to an element.

Multiple choice

How do you remove an event listener from an element in React?

  1. Using the removeEventListener() method

  2. Using the onClick() event handler

  3. Using the onEvent() method

  4. Using the handleEvent() method
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The removeEventListener() method is used to remove an event listener from an element in React. It is the most common way to remove an event listener from an element.

Multiple choice

Which of the following is not a valid way to create a controlled component in React?

  1. Using the value attribute

  2. Using the onChange event handler

  3. Using the useState() hook

  4. Using the useEffect() hook
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

useEffect() hook is not used to create a controlled component in React. The valid ways to create a controlled component are using the value attribute, the onChange event handler, and the useState() hook.

Multiple choice

What is the difference between inline event handlers and event handlers defined in the component class in React?

  1. Inline event handlers are defined directly in the HTML code, while event handlers defined in the component class are defined in the React component class

  2. Inline event handlers are more efficient than event handlers defined in the component class

  3. Inline event handlers are more secure than event handlers defined in the component class

  4. None of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Inline event handlers are defined directly in the HTML code, while event handlers defined in the component class are defined in the React component class.

Multiple choice

Which of the following is not a valid way to define an event handler in the component class in React?

  1. Using the onClick() method

  2. Using the onChange() method

  3. Using the onSubmit() method

  4. Using the handleEvent() method
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

handleEvent() method is not a valid way to define an event handler in the component class in React. The valid ways to define an event handler in the component class are using the onClick(), onChange(), and onSubmit() methods.

Multiple choice

Which of the following is not a valid way to implement event delegation in React?

  1. Using the addEventListener() method

  2. Using the onClick() event handler

  3. Using the onEvent() method

  4. Using the handleEvent() method
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

onClick() event handler is not a valid way to implement event delegation in React. The valid ways to implement event delegation in React are using the addEventListener(), onEvent(), and handleEvent() methods.

Multiple choice

Which of the following is a valid way to initialize state in a React component?

  1. Using the useState hook

  2. Using the setState method

  3. Using the constructor method

  4. Using the componentDidMount method
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The useState hook is the preferred way to initialize state in a React component. It allows you to declare a state variable and its initial value in a single line of code.

Multiple choice

Which lifecycle method is called when a React component is first mounted?

  1. componentDidMount

  2. componentWillMount

  3. componentDidUpdate

  4. componentWillUpdate
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The componentDidMount lifecycle method is called when a React component is first mounted. It is a good place to perform tasks such as fetching data from an API or setting up event listeners.

Multiple choice

Which lifecycle method is called when a React component is about to be updated?

  1. componentDidMount

  2. componentWillMount

  3. componentDidUpdate

  4. componentWillUpdate
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The componentWillUpdate lifecycle method is called when a React component is about to be updated. It is a good place to perform tasks such as updating the state of the component based on the new props.

Multiple choice

Which lifecycle method is called when a React component has been updated?

  1. componentDidMount

  2. componentWillMount

  3. componentDidUpdate

  4. componentWillUpdate
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The componentDidUpdate lifecycle method is called when a React component has been updated. It is a good place to perform tasks such as updating the UI of the component based on the new state.

Multiple choice

Which lifecycle method is called when a React component is about to be unmounted?

  1. componentDidMount

  2. componentWillMount

  3. componentDidUpdate

  4. componentWillUnmount
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The componentWillUnmount lifecycle method is called when a React component is about to be unmounted. It is a good place to perform tasks such as cleaning up event listeners or timers.

Multiple choice

What is the purpose of the shouldComponentUpdate lifecycle method?

  1. To determine if a React component should update

  2. To update the state of a React component

  3. To fetch data from an API

  4. To set up event listeners
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The shouldComponentUpdate lifecycle method is used to determine if a React component should update. It is a good place to perform a shallow comparison of the new props and state with the old props and state to determine if an update is necessary.

Multiple choice

Which lifecycle method is called when a React component receives new props?

  1. componentDidMount

  2. componentWillMount

  3. componentDidUpdate

  4. componentWillReceiveProps
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The componentWillReceiveProps lifecycle method is called when a React component receives new props. It is a good place to perform tasks such as updating the state of the component based on the new props.

Multiple choice

What is the purpose of the getDerivedStateFromProps lifecycle method?

  1. To update the state of a React component based on the new props

  2. To determine if a React component should update

  3. To fetch data from an API

  4. To set up event listeners
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The getDerivedStateFromProps lifecycle method is used to update the state of a React component based on the new props. It is a good place to perform tasks such as calculating new values or fetching data from an API.