ELSE is part of the IF.
ELSE can be used to have some javascript code run as a condition
other than the main stream logic (expression) in the IF statement.
You should already be fimilar with the IF logic.
This ELSE allows you to have code run when the expression in the IF
equates to a boolean false value.
Expressions that evaluate to a boolean false value are:
undefined, null, 0, false
All other things equate to a boolean true statement.
Very simple ELSE usage where these all output "It was False":
if (!1) document.write("It was True"); else document.write("It was False");
Note that "!" is "not" - so "not one" equates to boolean false.
if (0) document.write("It was True"); else document.write("It was False");
if (1 != 1) document.write("It was True"); else document.write("It was False");
Note that "!=" is the "is it not equal to" condition.
It follows that any complexity of the expression in the IF statement still results
in a boolean value. When it is false, the ELSE portion will run.
The last part to mention about ELSE's is the ELSE IF:
if (!1) document.write("!1");
else if (!2) document.write("!2");
else if (!0) document.write("!0");
else document.write("There were all false."):
This will output "!0" as this is the first boolean expression that evaluated to TRUE.
ELSEs associate with the nearest if that it can see in its scope.
