Data Types

Question 1

What is an object?

Answer 1

{} data stored inside curly brackets. Objects contain properties and methods. Examples of objects in JavaScript : Arrays, functions

Question 2

What is a primitive?

Answer 2

Primitives are the building blocks of JavaScript. Primitives are often described as limited data types. Examples: string, number, Boolean, undefined, null

Question 3

What does undefined mean in JavaScript?

Answer 3

Undefined means that the value has not been set.

Question 4

What does null mean in JavaScript?

Answer 4

Explicitly nothing.

Question 5

How do you tell if something is an object in JavaScript?

Answer 5

If it is not a primitive (string, number, Boolean, undefined or null) then it is an object

Question 6

{} ==={} what does this expression evaluate to? Why?

Answer 6

The expression returns false because although the objects contain the same data, they are separate objects. Essentially the expression could be rewritten as: is object1 === object2 ? No they are separate objects.

Question 7

Var houseA = {};
houseA === houseA

What does this expression evaluate to and why?

Answer 7

The expression evaluates to true. This is because we set a variable to an object and compared the variable to to itself. We are essentially comparing one object to itself