HTML and CSS Reference
In-Depth Information
EXAMPLE
5.10
<html>
<head>
<title>Logical NOT Operator</title>
</head>
<body bgcolor="lightblue">
<big>
<script type="text/javascript">
1
var answer = true
;
2
alert("Was true. Now it is " +
! answer
);
</script>
</big>
</body>
</html>
EXPLANATION
1
The Boolean value
true
is assigned to the variable
answer
.
2
The expression sent to the alert dialog box,
! answer
, negates the value
true
(not
true), making it
false
. (See Figure 5.15.)
Figure 5.15
The logical “not” operator changes true to false or false to true. The
!
operator caused
true
to become
false.
In summary, Example 5.11 illustrates the logical operators and the values they return.
EXAMPLE
5.11
<html>
<head>
<title>Logical (Boolean) Operators</title>
</head>
<body>
<h3>
<script type = "text/javascript">
1
var num1=50;
var num2=100;
var num3=0;
