Which symbol is used for string concatenation in JavaScript?

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

A). '55'

B). 10

C). 5

D). '10'

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

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

A). number

B). integer

C). float

D). string

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

A). _myVariable

B). 2ndVariable

C). $myVariable

D). my-Variable

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

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

A). const

B). let

C). var

D). constant

What will be the output of the following code: console.log('Hello ' + 'World');?

A). Hello World

B). Hello + World

C). Hello +World

D). HelloWorld

What will be the output of the following code: console.log(parseInt('10.5'));?

A). 10

B). 5

C). '10.5'

D). NaN (Not a Number)

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

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