Which of the following is an invalid identifier?

Can JavaScript identifiers include spaces?

A). Yes

B). No

C). Only in ES6

D). Only in strings

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

Which is a correct identifier for a variable?

A). 9variable

B). variable-9

C). variable_9

D). variable 9

Which of the following is a reserved word in JavaScript?

A). myVariable

B). function

C). let

D). number

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

A). undefined

B). null

C). 5

D). x

Which of these is an invalid identifier?

A). foo_bar

B). fooBar

C). foo-bar

D). foo$bar

Can an identifier be a single character?

A). Yes

B). No

C). Only in ES5

D). Only in ES6

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