React Component Lifecycle: A Comprehensive Guide for Beginners

Question 1

Which React lifecycle method has been deprecated and is no longer recommended for use?

Accepted Answer

componentWillReceiveProps

Answer

componentDidMount

Answer

componentWillUnmount

Answer

shouldComponentUpdate

Question 2

When is the componentWillUnmount lifecycle method invoked?

Accepted Answer

Just before a component is removed from the DOM.

Answer

When a component receives new props.

Answer

Immediately after a component is mounted.

Answer

When a component's state changes.

Question 3

What is the primary role of the componentDidUpdate lifecycle method?

Accepted Answer

To update the DOM in response to changes in props or state.

Answer

To capture the current props and state before an update occurs.

Answer

To determine if a component should update.

Answer

To initialize the component and its state.

Question 4

Which lifecycle method is used to set the initial state of a class component?

Accepted Answer

constructor

Answer

componentDidMount

Answer

getInitialState

Answer

render

Question 5

What does the shouldComponentUpdate lifecycle method return?

Accepted Answer

A boolean value indicating whether the component should update.

Answer

The updated props of the component.

Answer

The new state of the component.

Question 6

Which lifecycle method is triggered when a component receives new props?

Accepted Answer

componentWillReceiveProps

Answer

getSnapshotBeforeUpdate

Answer

componentDidUpdate

Answer

render

Question 7

What is the purpose of the getDerivedStateFromProps lifecycle method?

Accepted Answer

To derive new state based on changes in props.

Answer

To initialize the component's state.

Answer

To check if a component should update based on new props.

Question 8

Which lifecycle method is invoked immediately after a component is mounted?

Accepted Answer

componentDidMount

Answer

render

Answer

componentWillMount

Answer

constructor

Question 9

Explain the difference between the shouldComponentUpdate and componentDidUpdate lifecycle methods.

Accepted Answer

shouldComponentUpdate determines if a component should update, while componentDidUpdate is called after the update has occurred.

Answer

shouldComponentUpdate is called before componentDidUpdate.

Answer

componentDidUpdate is called before shouldComponentUpdate.

Question 10

Which lifecycle method is called when a component is about to receive new props?

Accepted Answer

componentWillReceiveProps

Answer

shouldComponentUpdate

Answer

componentDidUpdate

Answer

getSnapshotBeforeUpdate

Question 11

What is the purpose of the getSnapshotBeforeUpdate lifecycle method?

Accepted Answer

To capture the current props and state before an update occurs.

Answer

To check if a component should update based on new props.

Answer

To initialize the component's state.

Question 12

Which lifecycle method is called immediately after a React component is added to the web page?

Accepted Answer

componentDidMount

Answer

constructor

Answer

getDerivedStateFromProps

Answer

render

Question 13

Which lifecycle method is used to perform cleanup operations and remove event listeners when a component is unmounted?

Accepted Answer

componentWillUnmount

Answer

shouldComponentUpdate

Answer

componentDidUpdate

Answer

componentDidMount

Question 14

What is the primary purpose of the `shouldComponentUpdate` lifecycle method?

Accepted Answer

To optimize performance by preventing unnecessary re-renders.

Answer

To perform asynchronous data fetching.

Answer

To handle side effects when a component receives new props.

Question 15

In which order are the following lifecycle methods called during component creation: `constructor`, `getDerivedStateFromProps`, and `render`?

Accepted Answer

constructor -> getDerivedStateFromProps -> render

Answer

render -> constructor -> getDerivedStateFromProps

Answer

getDerivedStateFromProps -> constructor -> render

Question 16

What is the main difference between using `setState` and `this.setState`?

Accepted Answer

`setState` schedules a state update, while `this.setState` updates the state immediately (synchronously).

Answer

There is no difference between `setState` and `this.setState`.

Answer

`setState` is asynchronous, while `this.setState` is synchronous.

Question 17

Which lifecycle method is commonly used for asynchronous data fetching and side effect management?

Accepted Answer

componentDidMount

Answer

componentWillReceiveProps

Answer

shouldComponentUpdate

Answer

componentWillUpdate

Question 18

What is the purpose of using `getDerivedStateFromProps`?

Accepted Answer

To compute and update the state of a component based on changes in its props.

Answer

To optimize rendering performance by preventing unnecessary re-renders.

Answer

To handle side effects when a component receives new props.

Question 19

Which lifecycle method is invoked when a component is first rendered to the DOM?

Accepted Answer

componentDidMount

Answer

componentWillUpdate

Answer

componentWillReceiveProps

Question 20

What is a key advantage of using lifecycle methods over directly mutating state?

Accepted Answer

Lifecycle methods ensure predictable and controlled state updates.

Answer

Reduces the risk of side effects.

Answer

Improves code readability.

Answer

Enhances component reusability.

Question 21

Which lifecycle method can be used to perform cleanup operations before a component is unmounted?

Accepted Answer

componentWillUnmount

Answer

shouldComponentUpdate

Answer

componentDidMount

Answer

componentDidUpdate

Question 22

Which lifecycle method in React is designed to run just before a component is removed and detached from the DOM?

Accepted Answer

componentWillUnmount

Answer

componentDidUnmount

Answer

getDerivedStateFromProps

Answer

shouldComponentUpdate

Question 23

In React, which lifecycle method is specifically used to initialize state based on the initial set of props?

Accepted Answer

getDerivedStateFromProps

Answer

componentDidMount

Answer

shouldComponentUpdate

Answer

componentWillReceiveProps

Question 24

When props of a mounted React component change, which lifecycle method is triggered?

Accepted Answer

componentWillReceiveProps

Answer

shouldComponentUpdate

Answer

getDerivedStateFromProps

Answer

componentDidUpdate

Question 25

In React, which lifecycle method is used to perform side effects after a component has updated?

Accepted Answer

componentDidUpdate

Answer

shouldComponentUpdate

Answer

getDerivedStateFromProps

Answer

componentWillUpdate

Question 26

Which lifecycle method in React is invoked when a component is about to receive new props?

Accepted Answer

componentWillReceiveProps

Answer

getDerivedStateFromProps

Answer

componentDidUpdate

Answer

shouldComponentUpdate

Question 27

At the initial creation stage of a React component, which lifecycle method is the first to be executed?

Accepted Answer

constructor

Answer

shouldComponentUpdate

Answer

componentDidMount

Answer

getDerivedStateFromProps

Question 28

After a component has been mounted and rendered to the DOM, which lifecycle method is invoked?

Accepted Answer

componentDidMount

Answer

shouldComponentUpdate

Answer

componentWillUpdate

Answer

componentWillReceiveProps

Question 29

What is the primary purpose of the `componentWillUnmount` lifecycle method?

Accepted Answer

Execute cleanup actions and detach event listeners before the component is removed from the DOM.

Answer

Compare previous and current props to assess if a re-render is necessary.

Answer

Update the component's state prior to re-rendering.

Question 30

Which lifecycle method empowers a component to determine if it should update when props or state change?

Accepted Answer

shouldComponentUpdate

Answer

componentWillReceiveProps

Answer

componentDidUpdate

Answer

getDerivedStateFromProps

Question 31

In React components, what is the key distinction between `props` and `state`?

Accepted Answer

Props are immutable and controlled by the parent component while state is mutable and managed within the component itself.

Answer

Only props are immutable.

Answer

Both props and state are mutable.

Answer

Only state is immutable.

Question 32

Which lifecycle method is used to update a component's state in response to changes in its props?

Accepted Answer

getDerivedStateFromProps

Answer

componentDidUpdate

Answer

componentWillMount

Question 33

What is the purpose of the `render` lifecycle method?

Accepted Answer

Return a React element representing the component's current state.

Answer

Execute cleanup actions prior to component removal.

Answer

Determine if a re-render is required based on prop and state changes.

Answer

Update the component's state based on received props.

Question 34

Which lifecycle method is invoked when a component receives new props?

Accepted Answer

componentWillReceiveProps

Answer

componentDidMount

Answer

shouldComponentUpdate

Question 35

What is the primary benefit of using `React.memo` on a functional component?

Accepted Answer

Enhancing performance by preventing unnecessary re-renders through prop comparison.

Answer

Converting the functional component to a class component.

Answer

Automatically binding event listeners to the component.

Question 36

Which lifecycle method is employed to set up the component and its initial state?

Accepted Answer

constructor

Answer

componentDidMount

Answer

componentWillReceiveProps

Answer

render

Question 37

Which lifecycle method is called when a React component is first added to the DOM?

Accepted Answer

componentDidMount()

Answer

render()

Answer

componentWillUnmount()

Answer

constructor()

Question 38

Which lifecycle method allows you to perform cleanup actions before a component is removed from the DOM?

Accepted Answer

componentWillUnmount()

Answer

render()

Answer

componentDidMount()

Answer

shouldComponentUpdate()

Question 39

Which lifecycle method is used to update the component's state based on changes to its props?

Accepted Answer

getDerivedStateFromProps()

Answer

componentDidUpdate()

Answer

componentDidMount()

Answer

constructor()

Question 40

The `render()` method is called after `componentDidUpdate()`, regardless of whether the component's state or props change. Is this statement true or false?

Accepted Answer

True

Answer

Only if the state changes

Answer

Only if the props change

Answer

False

Question 41

Which lifecycle method helps optimize performance by allowing you to determine if a component needs to re-render?

Accepted Answer

shouldComponentUpdate()

Answer

componentDidUpdate()

Answer

getSnapshotBeforeUpdate()

Answer

componentDidMount()

Question 42

The `getSnapshotBeforeUpdate()` method is called before the DOM is updated. True or false?

Accepted Answer

True

Answer

False

Answer

Only if the props change

Answer

Only if the state changes

Question 43

Which lifecycle method is typically used to perform side effects related to changes in a component's state or props?

Accepted Answer

componentDidUpdate()

Answer

shouldComponentUpdate()

Answer

componentWillReceiveProps()

Answer

getSnapshotBeforeUpdate()

Question 44

Which lifecycle method is designed to handle errors that might occur during a component's lifecycle?

Accepted Answer

componentDidCatch()

Answer

componentWillUnmount()

Answer

render()

Answer

shouldComponentUpdate()

Question 45

Which lifecycle method is called immediately after a component is rendered for the first time?

Accepted Answer

componentDidMount()

Answer

componentWillMount()

Answer

componentWillReceiveProps()

Answer

componentDidUpdate()

Question 46

In which lifecycle method would you typically fetch data from an API to be displayed in your React component?

Accepted Answer

componentDidMount()

Answer

componentDidUpdate()

Answer

componentWillMount()

Answer

componentWillReceiveProps()

Question 47

What is the primary purpose of the `shouldComponentUpdate()` lifecycle method?

Accepted Answer

To determine whether the component needs to re-render based on changes in props or state, preventing unnecessary re-renders and improving performance.

Answer

To clean up resources before the component is unmounted.

Answer

To update the component's state after a prop change.

Question 48

Which lifecycle method is called **before** a component receives new props?

Accepted Answer

componentWillReceiveProps

Answer

componentWillUpdate

Answer

componentDidMount

Answer

componentDidUpdate

Question 49

What is the primary difference between `componentWillMount()` and `componentDidMount()`?

Accepted Answer

componentWillMount() is called before the component is rendered, while componentDidMount() is called immediately after the initial render has completed, effectively after the component is added to the DOM.

Answer

componentWillMount() handles state changes, while componentDidMount() handles prop changes.

Question 50

Which lifecycle method is called **before** a component updates due to changes in state or props?

Accepted Answer

componentWillUpdate

Answer

componentWillReceiveProps

Answer

componentDidUpdate

Answer

shouldComponentUpdate

Question 51

What is the purpose of the `componentWillUnmount()` lifecycle method?

Accepted Answer

To perform cleanup actions such as removing event listeners and clearing resources before the component is removed from the DOM, ensuring efficient resource management.

Answer

To re-render the component before it is unmounted.

Answer

To update the component's state before it is unmounted.

Question 52

Why is it important to understand the React component lifecycle?

Accepted Answer

It allows developers to control the behavior of components at different stages of their existence, enabling effective management of state, side effects, and performance.

Answer

It simplifies the process of rendering components.

Answer

It is essential for managing component state.

Question 53

A component's `state` is updated in the `componentDidMount()` lifecycle method. What might happen if you try to access that updated state within the `componentWillMount()` method?

Accepted Answer

The updated state will not be available in `componentWillMount()` because it is updated _afterwards_ in `componentDidMount()`. Attempting to access it will result in accessing the previous state value.

Answer

The component will immediately re-render.

Question 54

You are building a component that needs to perform an animation after it is rendered. Which lifecycle method would you use to trigger the animation?

Accepted Answer

componentDidMount

Answer

componentDidUpdate

Answer

componentWillMount

Answer

componentWillUpdate