In React what is used to pass data to a component from outside?
setState
render with arguments
props
PropTypes
Q.2.
What is the DOM?
Document Object Model
Data Object Model
Data Option Model
Documentation Object Model
Q.3.
Which of the following API is a MUST for every ReactJS component?
getInitialState
render
renderComponent
None of the above
Q.4.
What is a good use case for using a function while rendering a dynamic list of items
If we need to compute a value based on properties of items in the loop.
None. Functions should not be used while rendering a dynamic list.
To make the code shorter
None of the above
Q.5.
Which method is not part of ReactDOM?
ReactDOM.destroy()
ReactDOM.hydrate()
ReactDOM.createPortal()
ReactDOM.findDOMNode()
Q.6.
Which of the following is correct syntax for a button click event handler, foo?
<button onclick=this.foo()>
<button onclick=this.foo>
<button onClick={this.foo()}>
<button onClick={foo}>
Q.7.
What is a controlled input element?
An input element with the controlled flag
An input element whose value is being controlled by a component’s state
An input element that can only accept a list of characters
An input element that is controlled by the value of another input element
Q.8.
How do you write an inline style specifying 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'}}
Q.9.
At the highest level, React components have lifecycle events that fall into
Initialization
State/Property Updates
Destruction
All of these
Q.10.
What is the second argument for setState useful for?
To invoke code after the setState operation is done
To replace the state completely instead of the default merge action
To access the previous state before the setState operation
None of the above
Q.11.
What happens when the following render() method executes?<br /><br /> render(){<br /> let langs = ["Ruby","ES6","Scala"]<br /> return (<div><br /> {langs.map(it => <p>{it}</p>)}<br /> </div>)<br /> }<br />
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
Q.12.
How many elements does a react component return?
2 Elements
1 Element
Multiple Elements
None of These
Q.13.
What are the two ways that data gets handled in React?
state & props
services & components
Q.14.
Everything in react is
Component
Model
Method
Package
Q.15.
What function allows you to render React content in an HTML page?
React.mount()
ReactDOM.start()
ReactDOM.render()
React.render()
Q.16.
What is JSX?
it is a syntax extension to JavaScript.
JSX produces data.
Tool to control the data
Q.17.
What function can be used to update state?
setState()
updateState()
upState()
downState()
Q.18.
Who Develop React.js?
Apple
Facebook
Twitter
Google
Q.19.
When it is recommended to pass this.setState as a function instead of an object?
When the new state should completely replace the old state
When the new state depends on the old state
When the new state does not depend on the old state
None of the above
Q.20.
Which of the following below act as the input of a class-based component?
class and factory
render and mount
props
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