How to declare variables
without assigning values to them

var subtotal;      

// declares a variable named subtotal

 

var lastName, state, zipCode; 

// declares three variables

 

 

The assignment operators

=

+=

-=

*=

/=

%=

 

How to declare variables and assign values

var subtotal = 74.95;          // subtotal is 74.95

 

var salesTax = subtotal * .1;  // salesTax is 7.495

 

var isValid = false;           // Boolean value is false

 

var zipCode = "93711", state = "CA";   // two assignments

 

var firstName = "Ray", lastName = "Harris";

var fullName = lastName + ", " + firstName;

// fullName is "Harris, Ray"

 

How to code compound assignment statements

var subtotal = 24.50;

 

subtotal += 75.50;         // subtotal is 100

subtotal *= .9;            // subtotal is 90 (100 * .9)

 

var firstName = "Ray", lastName = "Harris";

var fullName = lastName;   // fullName is "Harris"

fullName += ", ";          // fullName is "Harris, "

fullName += firstName;     // fullName is "Harris, Ray"

 

var months = 120, message = "Months: ";

message += months;         // message is "Months: 120"