Object-Oriented JavaScript - Second Edition

Primitive data types

Any value that you use is of a certain type. In JavaScript, there are just a few primitive data types:

1. Number: This includes floating point numbers as well as integers. For example, these values are all numbers: 1, 100, 3.14.
2. String: These consist of any number of characters, for example "a", "one", and "one 2 three".
3. Boolean: This can be either true or false.
4. Undefined: When you try to access a variable that doesn't exist, you get the special value undefined. The same happens when you declare a variable without assigning a value to it yet. JavaScript initializes the variable behind the scenes with the value undefined. The undefined data type can only have one value – the special value undefined.
5. Null: This is another special data ...