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Unit 13: Building Object of JavaScript
Self Assessment Notes
Fill in the blanks:
9. The ............................. is used to work with dates and times.
10. Date objects are created with the ................................. constructor.
13.5 User Defined Objects
All user-defined objects and built-in objects are descendants of an object called Object.
13.5.1 The New Operator
The new operator is used to create an instance of an object. To create an object, the new operator
is followed by the constructor method.
In the following example, the constructor methods are Object(), Array(), and Date().
These constructors are built-in JavaScript functions.
var employee = new Object();
var books = new Array(“C++”, “Perl”, “Java”);
var day = new Date(“August 15, 1947”);
13.5.2 The Object () Constructor
A constructor is a function that creates and initializes an object. JavaScript provides a special
constructor function called Object () to build the object. The return value of the Object () constructor
is assigned to a variable.
The variable contains a reference to the new object.
Did u know? The properties assigned to the object are not variables and are not defined
with the var keyword.
This example demonstrates how to create an object:
<html>
<head>
<title>User-defined objects</title>
<script type=”text/javascript”>
var book = new Object(); // Create the object
book.subject = “Perl”; // Assign properties to the object
book.author = “Mohtashim”;
</script>
</head>
<body>
<script type=”text/javascript”>
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