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

Can JavaScript identifiers include spaces?

A). Yes

B). No

C). Only in ES6

D). Only in strings

Which characters are allowed in JavaScript identifiers?

A). Letters only

B). Letters and numbers only

C). Letters, numbers, $ and _

D). Any special characters

Which of the following is a valid identifier?

A). if

B). else

C). null

D). value1

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

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

A). Syntax error

B). 5

C). 10

D). Reference error

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

A). undefined

B). null

C). 5

D). x

Which of the following is a valid identifier name?

A). var

B). 123abc

C). _123abc

D). #abc123

Is let a valid identifier in JavaScript?

A). Yes

B). No

C). Only in ES6

D). Only in non-strict mode

Which of these is an invalid identifier?

A). foo_bar

B). fooBar

C). foo-bar

D). foo$bar