Which identifier is valid in strict mode?

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

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

A). undefined

B). null

C). 5

D). x

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

Which is a correct identifier for a variable?

A). 9variable

B). variable-9

C). variable_9

D). variable 9

Can identifiers start with a digit in JavaScript?

A). Yes

B). No

C). Only in ES5

D). Only in strict mode

Are JavaScript identifiers case-sensitive?

A). Yes

B). No

C). Only in ES6

D). Only in strict mode

Which of the following is a valid identifier?

A). if

B). else

C). null

D). value1

What is the maximum length of an identifier?

A). 255 characters

B). 31 characters

C). 64 characters

D). No limit

Is let a valid identifier in JavaScript?

A). Yes

B). No

C). Only in ES6

D). Only in non-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