JavaScript typeof

In JavaScript there are 5 different data types that can contain values:

• string

• number

• boolean

• object

• function

There are 6 types of objects:

• Object

• Date

• Array

• String

• Number

• Boolean

And 2 data types that cannot contain values:

• null

• undefined

The typeof Operator: use the typeof operator to find the data type of a JavaScript variable.

example:

typeof "John" // Returns "string"
typeof 3.14 // Returns "number"
typeof NaN // Returns "number"
typeof false // Returns "boolean"
typeof [1,2,3,4] // Returns "object"
typeof {name:'John', age:34} // Returns "object"
typeof new Date() // Returns "object"
typeof function () {} // Returns "function"
typeof myCar // Returns "undefined" *
typeof null // Returns "object"