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Defining Methods for an Object:
we need to complete the
definition of an object by assigning methods to it.
Example:
to show how to add a
function along with an object:
<html>
<head>
<title>User-defined objects</title>
<script type="text/javascript">
// Define a function which will work as a method
function addPrice(amount){
this.price = amount;
}
function book(title, author){
this.title = title;
this.author = author;
this.addPrice = addPrice; // Assign that method as property.
}
</script>
</head>
<body>
<script type="text/javascript">
var myBook = new book("Programming in C", "Balagurusamy");
myBook.addPrice(200);
document.write("Book title is : " + myBook.title + "<br>");
document.write("Book author is : " + myBook.author + "<br>");
document.write("Book price is : " + myBook.price + "<br>");
</script>
</body>
</html>
The with Keyword:
·
The with keyword is used as a kind of shorthand
for referencing an object's properties or methods.
·
The object specified as
an argument to with becomes the default object for the duration of the block
that follows.
·
The properties and
methods for the object can be used without naming the object.
Syntax:
with (object){
properties used without the object name and dot
}
Example:
<html>
<head>
<title>User-defined objects</title>
<script type="text/javascript">
// Define a function which will work as a method
function addPrice(amount){
with(this){
price = amount;
}
}
function book(title, author){
this.title = title;
this.author = author;
this.price = 0;
this.addPrice = addPrice; // Assign that method as property.
}
</script>
</head>
<body>
<script type="text/javascript">
var myBook = new book("Programming in C", "Balagurusamy");
myBook.addPrice(100);
document.write("Book title is : " + myBook.title + "<br>");
document.write("Book author is : " + myBook.author + "<br>");
document.write("Book price is : " + myBook.price + "<br>");
</script>
</body>
</html>
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