JavaScript Quiz

What is prototype inheritance in JavaScript?

• It allows objects to inherit properties and methods from other objects.

• It is a method for accessing elements in an array in JavaScript

• It is a feature for defining classes in JavaScript

• It is used to create new objects in JavaScript

How do you achieve inheritance in JS?

• Using prototype

• Using promises

• Using object

• No inheritance in JS

What is a Promise in JavaScript?

• A type of function in JavaScript

• A built-in method for sorting arrays in JavaScript

• A keyword used to declare variables in JavaScript

• An object representing the eventual completion or failure of an asynchronous operation.

How do you handle asynchronous operations using Promises in JavaScript?

• Use setTimeout to handle asynchronous operations

• Create a new Promise object and use the resolve and reject functions to handle the success and failure of the asynchronous operation.

• none of the above

• Use try and catch blocks to handle asynchronous operations

What are the states of a Promise in JavaScript?

• open, closed, and finished

• started, completed, and failed

• pending, fulfilled, and rejected

• waiting, approved, and denied

What is async/await in JavaScript?

• It is a feature that is only used for debugging purposes.

• It is a feature that has no impact on the way code is executed.

• It is a feature that allows you to write asynchronous code in a synchronous manner.

• It is a feature that allows you to write synchronous code in an asynchronous manner.

How do you use async/await with try/catch in JavaScript?

• Use the try/catch block to handle errors within the async function.

• Use switch/case statements to handle errors within the async function.

• Use a for loop to handle errors within the async function.

• Use if/else statements to handle errors within the async function.

What is the difference between map() and forEach() in JavaScript?

• map() and forEach() are interchangeable and can be used in place of each other.

• map() returns a new array with the results of calling a provided function on every element in the array, while forEach() executes a provided function once for each array element.

• map() is used for looping over the elements of an array, while forEach() is used for transforming the elements of an array.

• There is no difference between map() and forEach() in JavaScript.

How do you handle errors in a Promise in JavaScript?

• catch()

• then()

• finally()

• reject()

Predict the output

• Start
  End

• Start

• End

• Start
  End
  Resolved