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

Which of these is an invalid identifier?

A). foo_bar

B). fooBar

C). foo-bar

D). foo$bar

Which is a correct identifier for a variable?

A). 9variable

B). variable-9

C). variable_9

D). variable 9

Are JavaScript identifiers case-sensitive?

A). Yes

B). No

C). Only in ES6

D). Only in strict mode

Can JavaScript identifiers include spaces?

A). Yes

B). No

C). Only in ES6

D). Only in strings

What is a valid identifier in JavaScript?

A). 123abc

B). abc123

C). let

D). var

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?

A). if

B). else

C). null

D). value1

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

A). Syntax error

B). 5

C). 10

D). Reference error

Which of the following is a reserved word in JavaScript?

A). myVariable

B). function

C). let

D). number

Which identifier is valid in strict mode?

A). public

B). _public

C). 123public

D). public$