React Questions

March 16, 2023

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Deprecated: trim(): Passing null to parameter #1 ($string) of type string is deprecated in /home/u797631661/domains/codermantra.com/public_html/wp-includes/formatting.php on line 449

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React Questions

1 / 15

1. Which is not true about Virtual DOM in React JS?

A. can not directly update HTML

B. It uodates faster

C. Dom manipulation is very easy

D. too much memory wastage

2 / 15

2. What is the output of the below code ?

var Geeks=(props)=>
{
 return(
 

DSA Course 1
 

 

DSA Course 2
 

 );
}
ReactDOM.render( < DSA Course/ > ,mountNode)

A. DSA Course 1

B. DSA Course 2

C. DSA Course 1 DSA Course 2

D. Error

3 / 15

3. If you created a component called Dish and rendered it to the DOM, what type of element would be rendered?

 functioDish() {
  return < h1 > Mac and Cheese < /h1 > ;
}

ReactDOM.render(< Dish > , document.getElementById('root'));

A. div

B. section

C. component

D. h1

4 / 15

4. React component names must begin with an uppercase letter.

A. true

B. false

5 / 15

5. For controlled components in react

A. Source of truth is DOM

B. Source of truth can be anything

C. Source of truth is component

D. none of these

6 / 15

6. What is the use of React hooks?

A. To manage state and side effects in functional components

B. To manage styles in functional components

C. To manage state and side effects in class components

D. To manage styles in class components

7 / 15

7. How do you fix the syntax error that results from running this code?

const person =(firstName, lastName) =>
{
  first: firstName,
  last: lastName
}
console.log(person("Jill", "Wilson"))

A. Wrap the object in parentheses.

B. Call the function from another file.

C. Add a return statement before the first curly brace.

D. Replace the object with an array.

8 / 15

8. React.js is written in which of the following language?

A. c

B. c++

C. java

D. javascript

9 / 15

9. What is React.js?

A. Open-source JavaScript back-end library

B. JavaScript front-end library to create a database

C. Free and open-source JavaScript front-end library

D. None of the mentioned

10 / 15

10. How many ways of defining your variables in ES6?

A. 3

B. 1

C. 4

D. 2

11 / 15

11. Regarding JSX attributes, Which of the following statement is true?

A. Attribute names can be used in CAML case

B. Attribute names can be used in Sentence case

C. Any case can be used it does not matter like html

D. none of these

12 / 15

12. Using object literal enhancement, you can put values back into an object. When you log person to the console, what is the output?

const name = 'Rachel';
const age = 31;
const person = { name, age };
console.log(person);

A. {{name: "Rachel", age: 31}}

B. {name: "Rachel", age: 31}

C. {person: "Rachel", person: 31}}

D. {person: {name: "Rachel", age: 31}}

13 / 15

13. . What is the name of this component?

  class Clock extends React.Component {
  render() {
    return < h1 >  Look at the time: {time} < /h1>  ;
  }
}

A. Clock

B. It does not have a name prop.

C. React.Component

D. Component

14 / 15

14. React can only render elements in the root document element.

A. true

B. false

15 / 15

15. What is a react.js in MVC?

A. Controller

B. Middleware

C. Model

D. Router

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