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

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

A). var

B). let

C). const

D). Either B or C

What will be the output of the following code: if (true) { let b = 60; } console.log(b);

A). 60

B). undefined

C). Error

D). null

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

A). Yes

B). No

C). Only in functions

D). Only in loops

How do 'var' declarations handle hoisting?

A). They are not hoisted

B). Only the assignment is hoisted

C). Only the declaration is hoisted

D). Both declaration and assignment are hoisted

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 will be the output of the following code: const d = 90; d = 100; console.log(d);

A). 90

B). 100

C). Error

D). undefined

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: let c = 70; { let c = 80; console.log(c); } console.log(c);

A). 70 80 80

B). 80 80

C). Error

D). 70 80

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

A). Allows it

B). Silently ignores

C). Throws an error

D). Creates a new variable

Which keyword allows block-scoped variable declaration?

A). var

B). let

C). const

D). Both B and C