HTML and CSS Reference
In-Depth Information
EXAMPLE
8.10 (
CONTINUED
)
4
function show(obj, name)
{
//
Function to show the object's properties
var result = "";
5
for (var prop in obj)
{
6
result += name + "
.
"+
prop
+"="+
obj[prop]
+ "<br />";
}
7
return result;
}
</script>
</head>
<body bgcolor="lightblue">
<script type="text/javascript">
8
myBook = new book("JavaScript by Example", "Ellie",
"Prentice Hall");
9
document.write("<br /><b>" +
myBook.show(myBook, "myBook"
));
</script>
</body>
</html>
EXPLANATION
1
The function called
book
will define the properties and methods for a
book
object.
The function is a template for the new object. An instance of a new
book
object
will be created when this constructor is called.
2
This is the first property defined for the
book
object. The
this
keyword refers to
the current object.
3
A
show
property of the object is assigned a function name also called
show
, thus
creating a method for the object.
4
The function called
show()
is defined, tasked to display all the properties of the
object.
5
The special
for/in
loop executes a set of statements for each property of the object.
6
The name and value of each property is concatenated and assigned to a variable
called
result
. The value
obj[prop]
is used to key into each of the property values of
the
book
object.
7
The value of the variable
result
is sent back to the caller. Each time through the
loop, another property and value are displayed.
8
A
new book
object called
myBook
is created (instantiated).
9
The properties for the topic object are shown in the browser window; see Figure
8.12. Notice how the method and its definition are displayed.
