The Basics

Question 1

What data type is the following

1

Answer 1

Number

Question 2

What data type is the following

5.283

Answer 2

Number

Question 3

What data type is the following

“4”

Answer 3

String

Question 4

What data type is the following

False

Answer 4

Boolean

Question 5

Which variable statement allows only one assignment, but underlying values can be changed

Answer 5

const

Question 6

What is the scope of a var variable? Will declaring a var twice trigger an error? Will declaring a var twice trigger an error in strict mode?

Answer 6

The scope of a variable declared with var is its current execution context and closures thereof, which is either the enclosing function and functions declared within it, or, for variables declared outside any function, global. Duplicate variable declarations using var will not trigger an error, even in strict mode, and the variable will not lose its value, unless another assignment is performed.

MSDN var

Question 7

What basic data types are available for Javascript?

Answer 7

Boolean, String, Number

Question 8

What is the difference between === and ==?

Answer 8

=== is strict equality vs. == equality. Strings and Numbers in strict equality will be seen as false. i.e. 1==="1" would be false, but 1=="1" would be true.

Question 9

Which variable delcaration is safest to use?

Question 10

What is an expression?

Answer 10

A block of code that evaluates to a value.

Question 11

What is a statement?

Answer 11

A block of code that performs some kind of action.