How does 'let' handle variable re-declaration in the same scope?

What will be the output of the following code: let y = 10; let y = 20; console.log(y);

A). 10

B). 20

C). Error

D). undefined

What will be the output of the following code: var e = 110; if (true) { var e = 120; } console.log(e);

A). 110

B). 120

C). Error

D). undefined

What will happen if you declare a variable without 'var', 'let', or 'const'?

A). Creates a global variable

B). Creates a block-scoped variable

C). Creates a function-scoped variable

D). Throws an error

What is the scope of a variable declared with 'let' inside a loop?

A). Global

B). Function

C). Loop block

D). Entire script

Can you re-declare a variable using 'const' in the same scope?

A). Yes

B). No

C). Only in functions

D). Only in loops

Which keyword allows block-scoped variable declaration?

A). var

B). let

C). const

D). Both B and C

Which keyword should be used by default to declare variables in modern JavaScript?

A). var

B). let

C). const

D). Either B or C

Which keyword is used for declaring variables that should not change?

A). var

B). let

C). const

D). all of the above

Can 'const' be used to declare an array or object?

A). No, only primitives

B). Yes, but the reference can't change

C). Yes, and the content can't change

D). No

What will be the output of the following code: const z = 30; z = 40; console.log(z);

A). 30

B). 40

C). Error

D). undefined