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

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

A). undefined

B). null

C). 5

D). x

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

Which of these is an invalid identifier?

A). foo_bar

B). fooBar

C). foo-bar

D). foo$bar

Which of the following is a valid identifier?

A). if

B). else

C). null

D). value1

Which of the following is an invalid identifier?

A). _variable

B). var$

C). 2variable

D). variable2

Can an identifier be a single character?

A). Yes

B). No

C). Only in ES5

D). Only in ES6

Is let a valid identifier in JavaScript?

A). Yes

B). No

C). Only in ES6

D). Only in non-strict mode

What is the maximum length of an identifier?

A). 255 characters

B). 31 characters

C). 64 characters

D). No limit

Can JavaScript identifiers include spaces?

A). Yes

B). No

C). Only in ES6

D). Only in strings