Which identifier is valid in strict mode?

Which of the following is a reserved word in JavaScript?

A). myVariable

B). function

C). let

D). number

Can an identifier be a single character?

A). Yes

B). No

C). Only in ES5

D). Only in ES6

What is a valid identifier in JavaScript?

A). 123abc

B). abc123

C). let

D). var

Which of the following is a valid identifier name?

A). var

B). 123abc

C). _123abc

D). #abc123

Which of the following is an invalid identifier?

A). _variable

B). var$

C). 2variable

D). variable2

Are JavaScript identifiers case-sensitive?

A). Yes

B). No

C). Only in ES6

D). Only in strict mode

Can JavaScript identifiers include spaces?

A). Yes

B). No

C). Only in ES6

D). Only in strings

Which of these is an invalid identifier?

A). foo_bar

B). fooBar

C). foo-bar

D). foo$bar

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

A). undefined

B). null

C). 5

D). x

Is let a valid identifier in JavaScript?

A). Yes

B). No

C). Only in ES6

D). Only in non-strict mode