Test: Scope and Hoisting - 1 - Software Development MCQ

The scope of a variable determines where it is accessible within the program. It defines the region of code where a variable can be referenced.

The global scope in JavaScript refers to the scope that is accessible from anywhere in the program, including inside functions.

The "let" keyword is used to declare block-scoped variables in JavaScript. Block scope means the variable is accessible only within the block it is defined in.

Hoisting is a JavaScript behavior where variable declarations are moved to the top of their scope during the compilation phase, allowing variables to be accessed before they are declared.

Variables declared with var are hoisted to the top of their scope, allowing them to be accessed before they are declared. On the other hand, let variables are not hoisted and cannot be accessed before their declaration.

In JavaScript, variable declarations (not assignments) are hoisted to the top of their scope. So, the variable "x" is hoisted, but its value is not assigned at that point, resulting in the output "undefined".

Similar to the previous question, the variable "x" is hoisted to the top of the function scope. However, its value is not assigned until the line "var x = 10;" is reached, resulting in the output "undefined".

In this code, the variable "a" is declared using let, which is block-scoped. Since let variables are not hoisted, trying to access "a" before its declaration results in a ReferenceError.

This question is similar to the previous one. The variable "a" is declared using let, which is block-scoped. Accessing "a" before its declaration results in a ReferenceError.

In this code, the variable "x" is declared and assigned a value of 5. Inside the immediately invoked function expression (IIFE), a new variable "x" is declared using var and assigned a value of 10. Since the scope of the IIFE is separate from the outer scope, the console.log inside the IIFE prints "undefined" because the local "x" overshadows the outer "x".

The variable "x" is initially assigned a value of 2. Inside the IIFE, the value of "x" is changed to 5. After the IIFE, the value of "x" is 5, and the multiplication "x * 3" gives the result of 15.

The variable "sum" is initialized as 0. The "for" loop iterates from 0 to 4, adding each value of "i" to "sum". After the loop, the value of "i" is accessible outside the loop and is equal to 5.

Inside the IIFE, a new variable "x" is declared and assigned a value of 10. This "x" is local to the IIFE and does not affect the outer "x" with a value of 5. Therefore, the first console.log outputs 10, and the second console.log outputs 5.

The outer function "outer" has a variable "x" assigned a value of 1. Inside the function, an inner function "inner" is defined, which accesses and logs the value of "x". Before returning the inner function, the value of "x" is changed to 2. When the returned "fn" function is invoked, it outputs the value of "x", which is 2.

The "multiplyByTwo" function takes a number and returns an anonymous function. The anonymous function logs the value of the "result" variable, which is the input number multiplied by 2. When "multiplyByTwoFn" is invoked, it calls the returned anonymous function and outputs the value of "result", which is 10.