Which identifier is valid in strict mode?

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 reserved word in JavaScript?

A). myVariable

B). function

C). let

D). number

Is let a valid identifier in JavaScript?

A). Yes

B). No

C). Only in ES6

D). Only in non-strict mode

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

A). No error

B). Syntax error

C). Logical error

D). Runtime error

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

What is a valid identifier in JavaScript?

A). 123abc

B). abc123

C). let

D). var

Can JavaScript identifiers include spaces?

A). Yes

B). No

C). Only in ES6

D). Only in strings

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 the following is a valid identifier name?

A). var

B). 123abc

C). _123abc

D). #abc123