Which of the following is NOT a valid variable name in JavaScript?

Which variable declaration is appropriate if you want a variable to hold a constant value throughout the program execution?

A). let

B). var

C). const

D). constant

What will be the value of x after the following code executes: let x = '5' + 5;?

A). '55'

B). 10

C). 5

D). '10'

Which keyword is used to declare a constant variable in JavaScript?

A). const

B). let

C). var

D). constant

What is the purpose of the NaN (Not a Number) value in JavaScript?

A). To represent a number that is not a valid JavaScript number

B). To represent a zero value

C). To represent an infinite value

D). To represent an empty string

What is the keyword used to declare variables in JavaScript?

A). let

B). variable

C). var

D). const

Which data type is used to represent whole numbers in JavaScript?

A). number

B). integer

C). float

D). string

What is the scope of a variable declared using the let keyword in JavaScript?

A). Block scope

B). Function scope

C). Global scope

D). Local scope

What happens if you declare a variable without initializing it in JavaScript?

A). It will throw a syntax error

B). It will assign the variable a value of undefined

C). It will automatically assign a value to the variable

D). It will assign the variable a value of null

What will be the value of x after the following code executes: let x = 10; x += 5;?

A). 15

B). 5

C). 10

D). undefined

Which symbol is used for string concatenation in JavaScript?

A). +

B). -

C). *

D). /