Can identifiers start with a digit in JavaScript?

Which of the following is a valid identifier name?

A). var

B). 123abc

C). _123abc

D). #abc123

Which of the following is a valid identifier?

A). if

B). else

C). null

D). value1

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

Are JavaScript identifiers case-sensitive?

A). Yes

B). No

C). Only in ES6

D). Only in strict mode

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

Is let a valid identifier in JavaScript?

A). Yes

B). No

C). Only in ES6

D). Only in non-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 be the result of using a reserved word as an identifier?

A). No error

B). Syntax error

C). Logical error

D). Runtime error

Which of the following is a reserved word in JavaScript?

A). myVariable

B). function

C). let

D). number