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if(Ret=="castle") {
location = 'ch03_1.html';
else {
alert("Please try again")

The if-then statement

The second line of the function is an if-then statement. It tells the computer that if the variable Ret equals "castle" then change the URL location to ch03_1.html. Otherwise, show the alert box which says "Please try again."

Here is the format of an if-then statement:
IF (a comparison)
{ sequence if the comparison is true }

ELSE { sequence is the comparison is false }

For example, let's say you've just had the reader complete a form which included their age. You want all Senior Citizens to get one message, and everyone else to get another when they submit the form.

age=form.age.valuetransfer the contents of the age box on the form to a variable called age.
if (age>=65)The if statement begins with the question in parentheses.
{alert("Your form has been submitted. Ask about our Senior Discounts") }
The alert box will be displayed if the question is true, age IS greater or equal to 65
ELSE {alert("Your form has been submitted.") }
The alert box command following the word ELSE will only be displayed if the question is false, and age IS NOT greater or equal to 65.

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