Which characters are allowed in JavaScript identifiers?

Which of these is an invalid identifier?

A). foo_bar

B). fooBar

C). foo-bar

D). foo$bar

What is the output of the following code: var x = 5, x = 10;

A). Syntax error

B). 5

C). 10

D). Reference error

Can JavaScript identifiers include spaces?

A). Yes

B). No

C). Only in ES6

D). Only in strings

What is the maximum length of an identifier?

A). 255 characters

B). 31 characters

C). 64 characters

D). No limit

Can an identifier be a single character?

A). Yes

B). No

C). Only in ES5

D). Only in ES6

What does the following code do: var $ = 5;

A). Throws an error

B). Creates a variable named $

C). Creates a variable named var

D). None of the above

Are JavaScript identifiers case-sensitive?

A). Yes

B). No

C). Only in ES6

D). Only in strict mode

Which of the following is a reserved word in JavaScript?

A). myVariable

B). function

C). let

D). number

Which of the following is a valid identifier?

A). if

B). else

C). null

D). value1

Can identifiers start with a digit in JavaScript?

A). Yes

B). No

C). Only in ES5

D). Only in strict mode