Which keyword is used to declare a variable in JavaScript?

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

A). var

B). let

C). const

D). Both let and const

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

A). myVar

B). $myVar

C). _myVar

D). 123myVar

Which statement is true about variables in JavaScript?

A). They must be declared before use

B). They can only hold numbers

C). They are statically typed

D). They are strongly typed

What will be the output of the following code?

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

A). 10

B). undefined

C). Error

D). null

Which of the following is a valid variable name in JavaScript?

A). 2name

B). _name

C). #name

D).

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 is the correct syntax for declaring a variable in JavaScript?

A). let myVar = 5;

B). myVar let = 5;

C). 5 = let myVar;

D). let = myVar 5;

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

A). Variable names can start with a number

B). Variable names are case-insensitive

C). Variable names can include spaces

D). Variable names are case-sensitive

What is the difference between let and var?

A). let is function-scoped, var is block-scoped

B). let is block-scoped, var is function-scoped

C). Both are block-scoped

D). Both are function-scoped

What will be the output of the following code?

let x; console.log(x);

A). null

B). undefined

C). 0

D). NaN