Data Types

JavaScript has only four types of data, (you do not declare the type in var):

numeric

:

• integers such as 2,22 and 2,222,000 or
• floating point values like 23.42, -56.01 and 2E45.
• No need to differentiate between
• in fact variables can change type within program.

strings

:

• collections of characters that are not numbers.
• All of the following are strings:

  "David", 
  "David Marshall"
  "12345.432".
  

• put quotes around the value to a assign a variable:

  name = "David Marshall";
  name = 'David Marshall';
  str  = "34.45";
  

Boolean

:

• variables can hold the values true and false.
• used a lot in conditional tests (later).

null

:

• used when you don't yet know something.
• A null value means one that has not yet been decided.
• It does not mean nil or zero and should NOT be used in that way.