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React Basics
1/25
___ can be done while multiple elements need to be returned from a component.
Abstraction
Packing
Insulation
Wrapping
Next >
2/25
Which is the right way of accessing a function fetch() from an h1 element in JSX?
<h1>{fetch()}</h1>
<h1>${fetch()}</h1>
<h1>{fetch}</h1>
<h1>${fetch}</h1>
Next >
3/25
Which of the following methods in a React Component should be overridden to stop the component from updating?
willComponentUpdate
shouldComponentUpdate
componentDidUpdate
componentDidMount
Next >
4/25
What is used to pass data to a component from outside?
setState
render with arguments
PropTypes
props
Next >
5/25
Which of the following is the correct syntax for a button click event handler foo?
<button onclick={this.foo()}>
<button onclick={this.foo}>
<button onClick={this.foo()}>
<button onClick={this.foo}>
Next >
6/25
How do you write an inline style which specifies the font-size:12px and color:red; in JSX?
style={{font-size:12,color:'red'}}
style={{fontSize:'12px',color:'red'}}
style={fontSize:'12px',color:'red'}
style={{font-size:12px,color:'red'}}
Next >
7/25
What is state in React?
A persistant storage.
An internal data store (object) of a component.
Next >
8/25
What is ReactJS?
Server side Framework
User-interface framework
Library for building interaction interfaces
Next >
9/25
What are the two ways that data gets handled in React?
state & props
services & components
Next >
10/25
What disadvantages does ReactJS have?
It is only a view layer. You have to plug your code for Ajax requests, events and so on.
The library is pretty large.
The learning curve can be slow.
All of the above options
Next >
11/25
Choose the right answer about JSX.
JSX is faster as it performs optimization while compiling code to JavaScript
JSX is a syntax notation for JavaScript XML
JSX provides expressiveness of JavaScript along with HTML, like template syntax
All of the above options
Next >
12/25
How do you create a ref in a class component in React?
React.createRef()
React.ref()
this.ref.create()
new Ref()
Next >
13/25
Which method is necessary to define in a class component in React?
componentDidMount()
shouldComponentUpdate()
render()
getDerivedStateFromProps()
Next >
14/25
What is the purpose of React Router?
To manage global state
For conditional rendering
To handle navigation and routing
To connect to external APIs
Next >
15/25
In React, what is the purpose of the 'Context' API?
To enhance performance
For managing component lifecycle
To share data across components without prop drilling
To handle form inputs
Next >
16/25
What is the significance of the 'key' prop when rendering a list of items in React?
It is used for styling the list items
It helps React identify which items have changed
It is a required prop for all list items
It increases the rendering speed of the list
Next >
17/25
What does 'React.Fragment' do?
It groups a list of children without adding extra nodes to the DOM
It is a method to optimize performance
It is used to fragment a component into smaller components
It is a way to render components asynchronously
Next >
18/25
What is the purpose of React's 'useCallback' hook?
To memorize a function instance between renders
To call a function as a callback after state changes
To handle API calls efficiently
To update the state based on previous state
Next >
19/25
How can you prevent a function from being called too frequently in React, such as during window resizing?
Using shouldComponentUpdate
Using PureComponent
Using debounce or throttle techniques
Using useEffect with an empty dependency array
Next >
20/25
In React, what is a 'higher-order component' (HOC)?
A component with higher z-index
A component that returns another component
A stateful component
A component that renders HTML elements
Next >
21/25
How do you share state between two components that are not parent-child in React?
Using global variables
Using the Context API
Passing props through intermediate components
Using a state management library like Redux
Next >
22/25
What is the purpose of 'useReducer' in React?
To handle component lifecycle
For state management using a reducer function
To reduce the bundle size of a React app
To optimize rendering performance
Next >
23/25
What is JSX in React?
A JavaScript-based styling language
A syntax extension for JavaScript
A new programming language based on JavaScript
A framework for building user interfaces
Next >
24/25
What are 'fragments' in React?
Tools for memory management
Components that return multiple elements
A pattern for prop validation
Parts of the component's state
Next >
25/25
In React, how do you pass data from a parent component to a child component?
Using context
Via global variables
Through props
By setting state in the child
Next >
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