Values and Variables

In JavaScript, a piece of information is a value. There are different kinds of values; the kind you're most familiar with are numbers. A string value is a word or words enclosed in quotes. Other kinds of JavaScript values are listed in Table 1.2.

Table 1.2. Value Types

Type	Description	Example
Number	Any numeric value	3.141592654
String	Characters inside quote marks	"Hello, world!"
Boolean	True or False	true
Null	Empty and meaningless
Object	Any value associated with the object
Function	Value returned by a function

Variables contain values. For example, the variable myName is assigned the string "Dori". Another way to write this is myName="Dori". The equals sign can be read as "is set to." In other words, the variable myName now contains the value "Dori".

Operators

Operators are the symbols used to work with variables. You're already familiar with operators from simple arithmetic; plus and minus are operators. See Table 1.3 for the full list of operators.

Table 1.3. Operators

Operator	What It Does
x + y (Numeric)	Adds x and y together
x + y (String)	Concatenates x and y together
x - y	Subtracts y from x
x * y	Multiplies x and y together
x / y	Divides x by y
x % y	Modulus of x and y (i.e., the remainder when x is divided by y)
x++, ++ x	Adds one to x (same as x = x + 1)
x--, --x	Subtracts one from x (same as x = x - 1)
-x	Reverses the sign on x