Quiz React Basic
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Test your knowledge with W3docs’ basic quiz made especially for beginners in React JS. Pass the test and get a Certificate of achievement!
The Test
The test contains 20 questions and there is no time limit. The test is not official, it’s just a nice way to see how much you know about React JS.
Count Your Score
You will get 5% for each correct answer. At the end of the Quiz, your total score will be displayed out of 100% maximum score.
Enrich your knowledge
At the end of the quiz you can see all the questions with the right answers. There will also be notes about the answers which will lead you to the appropriate page on the platform to enrich your knowledge. Read our HTML tutorial if you are not sure that you are ready for the quiz.
Quiz Answers
React is mainly used for building _.
Database
Connectivity
User interface
Design Platform
Ans. User interface
The lifecycle methods are mainly used for _.
keeping track of event history
enhancing components
freeing up resources
none of the above
Ans. freeing up resources
_ can be done while multiple elements need to be returned from a component.
Abstraction
Packing
Insulation
Wrapping
Ans. Wrapping
Which is the right way of accessing a function fetch() from an h1 element in JSX?
{fetch()}
${fetch()}
{fetch}
${fetch}
Ans. h1>{fetch()}</h1
Which of the following methods in a React Component should be overridden to stop the component from updating?
willComponentUpdate
shouldComponentUpdate
componentDidUpdate
componentDidMount
Ans shouldComponentUpdate
What is used to pass data to a component from outside?
setState
render with arguments
PropTypes
props
Ans. Props
Which of the following methods in a React Component is called after the component is rendered for the first time?
componentDidUpdate
componentDidMount
componentMounted
componentUpdated
Ans. componentDidMount
Which of the following is the correct syntax for a button click event handler foo?
Ans. button onClick={this.foo}
What will happen if you call setState() inside render() method?
Repetitive output appears on the screen
Duplicate key error
Stack overflow error
Nothing happens
Ans. Stack overflow error
What will happen if the following render() method executes?
render(){
let langs = [“Ruby”,”ES6″,”Scala”]
return ( {langs.map(it => {it})} )
}
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
Ans. Displays the list of languages in the array
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’}}
Ans. style={{fontSize:’12px’,color:’red’}}
What advantages does ReactJS have?
Increases the application’s performance with Virtual DOM
JSX makes a code that is easy to read and write
It renders both on client and server side
Easy to integrate with other frameworks(Angular, BackboneJS) since it is only a view library
All of the above
Ans. All of the above
What is state in React?
A persistant storage.
An internal data store (object) of a component.
Ans. An internal data store (object) of a component.
What is ReactJS?
Server side Framework
User-interface framework
Library for building interaction interfaces
Ans. Library for building interaction interfaces
What are the two ways that data gets handled in React?
state & props
services & components
Ans. state & props
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
Ans. All of the above options
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
Ans. All of the above options
React merges the object provided into the current state using _.
setState()
State()
Ans. setState()
The arbitrary inputs of components are called _.
Keys
Props
Elements
Ref
Ans. Props
Ref is used for referring an element or component returned by _.
react()
render()
reduce()
refer()
Ans. render()