typeof is the ‘official’ function that one uses to get the type in javascript, however in certain cases it might yield some unexpected results …

1. Strings

typeof "String" or

typeof Date(2011,01,01)

“string”

2. Numbers

typeof 42

“number”

3. Bool

typeof true (valid values true and false)

“boolean”

4. Object

typeof {} or

typeof [] or

typeof null or

typeof /aaa/ or

typeof Error()

“object”

5. Function

typeof function(){}