Which of these is an invalid identifier?

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

What will the following code output: var x; x = 5; var y = x;

A). undefined

B). null

C). 5

D). x

Is let a valid identifier in JavaScript?

A). Yes

B). No

C). Only in ES6

D). Only in non-strict mode

Can JavaScript identifiers include spaces?

A). Yes

B). No

C). Only in ES6

D). Only in strings

Can identifiers start with a digit in JavaScript?

A). Yes

B). No

C). Only in ES5

D). Only in strict mode

Which identifier is valid in strict mode?

A). public

B). _public

C). 123public

D). public$

Are JavaScript identifiers case-sensitive?

A). Yes

B). No

C). Only in ES6

D). Only in strict mode

What is a valid identifier in JavaScript?

A). 123abc

B). abc123

C). let

D). var

Can an identifier be a single character?

A). Yes

B). No

C). Only in ES5

D). Only in ES6

Which of the following is a valid identifier?

A). if

B). else

C). null

D). value1