ReactJS Quiz Set - 4

Question 1

React is mainly used for building ___.

• Database

• Connectivity

• User interface

• Design Platform

Question 2

The lifecycle methods are mainly used for ___.

• keeping track of event history

• enhancing components

• freeing up resources

• none of the above

Question 3

___ can be done while multiple elements need to be returned from a component

• Abstraction

• Packing

• Insulation

• Wrapping

Question 4

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>

Question 5

Which of the following methods in a React Component should be overridden to stop the component from updating?

• willComponentUpdate

• shouldComponentUpdate

• componentDidUpdate

• componentDidMount

Question 6

What is used to pass data to a component from outside?

• setState

• render with arguments
  
  

• PropTypes

• props

Question 7

Which of the following methods in a React Component is called after the component is rendered for the first time?

• componentDidUpdate

• componentDidMount

• componentMounted
  

• componentUpdated

Question 8

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}>

Question 9

What will happen if you call setState() inside render() method?

• Repetitive output appears on the screen
  
  

• Duplicate key error

• 
  Stack overflow error

• Nothing happens

Question 10

What will happen if the following render() method executes?
render(){
let langs = ["Ruby","ES6","Scala"]
return <div>{langs.map(it => <p>{it}</p>)}</div>
}

• Displays the list of languages in the array

• Error. Cannot use direct JavaScript code in JSX
  
  

• Displays nothing

• Error. Should be replaced with a for..loop for correct output