Is let a valid identifier in JavaScript?

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

What is a valid identifier in JavaScript?

A). 123abc

B). abc123

C). let

D). var

Which of the following is an invalid identifier?

A). _variable

B). var$

C). 2variable

D). variable2

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

A). Syntax error

B). 5

C). 10

D). Reference error

Which identifier is valid in strict mode?

A). public

B). _public

C). 123public

D). public$

Which of these is an invalid identifier?

A). foo_bar

B). fooBar

C). foo-bar

D). foo$bar

Which of the following is a reserved word in JavaScript?

A). myVariable

B). function

C). let

D). number

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

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