What is a valid identifier in JavaScript?

Which characters are allowed in JavaScript identifiers?

A). Letters only

B). Letters and numbers only

C). Letters, numbers, $ and _

D). Any special characters

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

Can identifiers start with a digit in JavaScript?

A). Yes

B). No

C). Only in ES5

D). Only in strict mode

Which of the following is a valid identifier?

A). if

B). else

C). null

D). value1

Are JavaScript identifiers case-sensitive?

A). Yes

B). No

C). Only in ES6

D). Only in strict mode

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

A). undefined

B). null

C). 5

D). x

Which is a correct identifier for a variable?

A). 9variable

B). variable-9

C). variable_9

D). variable 9

Which of these is an invalid identifier?

A). foo_bar

B). fooBar

C). foo-bar

D). foo$bar

What will be the result of using a reserved word as an identifier?

A). No error

B). Syntax error

C). Logical error

D). Runtime error

Can JavaScript identifiers include spaces?

A). Yes

B). No

C). Only in ES6

D). Only in strings