Which keyword allows block-level scope in ES6?

What is the primary difference between var and let?

A). Scope

B). Initialization

C). Data type

D). Assignment

What happens if you try to access a let variable before its declaration?

A). Returns undefined

B). Throws a ReferenceError

C). Returns null

D). Returns an empty string

What will the following code output: { let y = 5; { let y = 10; console.log(y); } }?

A). 5

B). 10

C). undefined

D). ReferenceError

Which keyword should be used for a variable that might be reassigned?

A). const

B). let

C). var

D). function

What will the following code output: { const a = 10; a = 20; }?

A). 10

B). 20

C). undefined

D). TypeError

What is the temporal dead zone in ES6?

A). Time between function calls

B). Period between variable declaration and initialization

C). Time between two loops

D). Interval between event listeners

What is the output of the following code: let z = 3; z = 5; console.log(z);?

A). 3

B). 5

C). undefined

D). ReferenceError

Which of the following statements about const and objects is true?

A). Objects declared with const are immutable

B). Properties of objects declared with const can be changed

C). The reference of objects declared with const can be changed

D). const cannot be used with objects

Can a const variable be declared without an initial value?

A). Yes

B). No

C). Only in strict mode

D). Only if it is an object

What error will the following code produce: const PI; PI = 3.14;?

A). SyntaxError

B). TypeError

C). ReferenceError

D). No error