What will be the output of the following code: let x = 10; { let x = 20; } console.log(x);?
A). 10
B). 20
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
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
What is the primary difference between var and let?
A). Scope
B). Initialization
C). Data type
D). Assignment
What is the value of a const variable once it is assigned?
A). Can be changed later
B). Cannot be changed later
C). Depends on the data type
D). Undefined initially
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
What error will the following code produce: const PI; PI = 3.14;?
A). SyntaxError
B). TypeError
C). ReferenceError
D). No error
Can a let variable be redeclared in the same scope?
A). Yes
B). No
C). Only if it is a string
D). Only if it is a number
Can const variables be reassigned in nested scopes?
A). Yes
B). No
C). Only if they are strings
D). Only in strict mode