Which keyword allows block-level scope in ES6?
A). var
B). let
C). function
D). var and function
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 output of the following code: let z = 3; z = 5; console.log(z);?
A). 3
B). 5
C). undefined
D). ReferenceError
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
Can a variable declared with let be hoisted?
A). Yes, partially
B). No
C). Yes, fully
D). Only in strict mode
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 const be used for objects and arrays?
A). No
B). Yes
C). Only for arrays
D). Only for objects
What error will the following code produce: const PI; PI = 3.14;?
A). SyntaxError
B). TypeError
C). ReferenceError
D). No error