JavaScript Objects

JavaScript supports programming with objects. Obkects a way of organizing the variables. The different screen elements such as Web Pages, forms, text boxes, image, and buttons are treated as objects.

Properties and Methods


Every objrcts has it's own propeties and methods.

• Properties define the characteristics of an object.

          Examples : color, lenght, name, height, width

• Methods are the actions that the object can perform or that can be performed on the object.

          Examples : alert, confirm, write, open, close

Naming Objects

• Objects are organized in a hierarchy. To refer to an object use :

          objectName

• To refer to a property of an object use :

          objectName.propertyName

• To refer a method of an object use :

          objectName.methodName()

Build-In Objects

Some of the built-in language objects of JavaScript offer more advanced operations such as :

• Math - provides for math calculation
• Date - provides date and time information
• String - provides for string manipulation

Math Object

The Math object provides methods for many mathematical calculations, including : abs(), pow(), random(), round(), sqrt().

format : Math.method(#)

Math Example

• keep the "userdefined.html" file open
• Put the cursor in the BODY section and enter :

<SCRIPT language="JavaScript">
var theNumber=3.14
myNum=Math.round(theNumber)
</SCRIPT>

• Save the changes and Refresh the page

Date Object


The Date object provides the day, date, and time information.

Format : dateObject.method()

Date Example

• Keep the "userdefined.html" file open
• Pit the cursor in the BODY section and enter :

<SCRIPT language="JavaScript">
var rightNow=new Date()
theYear=rightNow.getFullYear()
</SCRIPT>

• Save the changes and Refresh the page

String Object

The String object provides methods and properties for tring manipulation and formatting.

Format : stringName.method()

String Example

• Keep the "userdefined.html" file open
• Put the cursor after the Date example and enter :

<SCRIPT language="JavaScript">
var theString="my name"
varPrintString=theString.bold()
varnumChars=theString.length
</SCRIPT>

• Save the changes and Refresh the page

SEE VIDEO






source code : www.youtube.com

Posted in: JavaScript Tutorial