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: console.log(a); var a = 50;
A). 50
B). undefined
C). Error
D). null
What is the default scope of variables declared with the 'var' keyword in JavaScript?
A). Block scope
B). Function scope
C). Module scope
D). Block and function scope
How does 'let' differ from 'var' in terms of scope?
A). No difference
B). Function-scoped
C). Block-scoped
D). Global-scoped
Which keyword allows block-scoped variable declaration?
A). var
B). let
C). const
D). Both B and C
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
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
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
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