JavaScript & ES6 Quiz

What is the output of typeof null in JavaScript?

• "null"

• "object"

• "undefined"

• "number"

Which of the following is a feature of ES6?

• var declarations

• Arrow functions

• with statements

• Function hoisting

What does the let keyword do in JavaScript?

• Declares a variable with global scope

• Declares a block-scoped variable

• Declares a constant variable

• Declares a variable hoisted to the top

Which method is used to merge two or more arrays in JavaScript?

• merge()

• concat()

• append()

• combine()

What is a pure function?

• A function that modifies global variables

• A function that returns different outputs for the same inputs

• A function with no side effects and consistent outputs

• A function that relies on external state

What does the map() function do in JavaScript?

• Filters elements in an array

• Reduces an array to a single value

• Transforms each element in an array

• Finds the first matching element

Which of the following is a higher-order function?

• parseInt()

• setTimeout()

• Math.random()

• JSON.stringify()

What is the purpose of an IIFE (Immediately Invoked Function Expression)?

• To create a global variable

• To execute a function immediately and create a new scope

• To delay function execution

• To define a class

What is recursion in programming?

• A function that calls itself

• A loop that runs indefinitely

• A function that returns another function

• A method to sort arrays

In JavaScript, what is prototypal inheritance?

• Inheriting properties from a parent class

• Sharing methods through the prototype chain

• Creating private variables

• Overriding built-in methods