Which of the following is true about variable naming conventions in JavaScript?

Which of the following is true about 'const' variables in JavaScript?

A). They can be redeclared

B). They cannot be reassigned

C). They can be reassigned

D). They are always undefined

Which keyword should be used to declare a block-scoped variable?

A). var

B). let

C). const

D). Both let and const

Which keyword is used to declare a variable in JavaScript?

A). var

B). let

C). const

D). All of the above

What is hoisting in JavaScript?

A). Function call before declaration

B). Variable declared at the top

C). Variable and function declaration are moved to the top

D). Variable scope

Can you reassign a value to a variable declared with let?

A). Yes

B). No

C). Only in strict mode

D). Only inside a block

Which of the following will cause an error?

A). let a = 10; a = 20;

B). const a = 10; a = 20;

C). var a = 10; a = 20;

D). None of the above

Which of the following is NOT a valid variable name in JavaScript?

A). myVar

B). $myVar

C). _myVar

D). 123myVar

Can variables declared with 'var' be redeclared in the same scope?

A). Yes

B). No

C). Only inside a function

D). Only inside a loop

What will be the output of the following code?

console.log(a); var a = 10;

A). 10

B). undefined

C). Error

D). null

What will be the output of the following code?

var a = 1; { var a = 2; } console.log(a);

A). 1

B). 2

C). undefined

D). ReferenceError