Variables and data types

Note These notes follow on from [[Javascript - Absolute Basics]]

Variables

A container for a value so that it can be reused

Declaring a variable

Here's the basic syntax:

var firstname = "John";

He uses single quotes and says single quotes are more 'modern' :P

5 basic data types in JavaScript

1. Number: Floating point numbers, for decimals and integers
2. String: Sequence of characters, used for text
3. Boolean: Logical data type that can only be TRUE or FALSE
4. Undefined: Data type of a variable that does not have a value yet
5. Null: Also means 'non-existent'

In JavaScript, all numbers are Floating Point, there are no distinct number types.

Best Practice - Always give variables a meaningful name

Best Practice - JavaScript uses CamelCase for its variables

Rules

• You cannot name a variable
  • With a keyword
  • By starting it with anything but
    • character
    • underscore
    • dollar sign