Which identifier is valid in strict mode?

Which of the following is a valid identifier?

A). if

B). else

C). null

D). value1

Can JavaScript identifiers include spaces?

A). Yes

B). No

C). Only in ES6

D). Only in strings

What will happen if you declare a variable with the name undefined?

A). Syntax error

B). Declares a variable

C). Throws a runtime error

D). Reassigns undefined

What is the maximum length of an identifier?

A). 255 characters

B). 31 characters

C). 64 characters

D). No limit

Which characters are allowed in JavaScript identifiers?

A). Letters only

B). Letters and numbers only

C). Letters, numbers, $ and _

D). Any special characters

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

A). undefined

B). null

C). 5

D). x

Which of these is an invalid identifier?

A). foo_bar

B). fooBar

C). foo-bar

D). foo$bar

Which of the following is an invalid identifier?

A). _variable

B). var$

C). 2variable

D). variable2

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 is a correct identifier for a variable?

A). 9variable

B). variable-9

C). variable_9

D). variable 9