Javascript Oop

JAVASCRIPT OOP

Introduction
//adding a custom property to a prebuilt object var myimage=new Image() myimage.size="26k" /*adding a custom property to the custom object "circle"*/ //First, create the custom object "circle" function circle(){ }
var smallcircle=new circle()
smallcircle.pi=3.14159
It will not work when a new object will created from circle as not inherited to it.

Using the prototype object to add custom properties to objects
//First, create the custom object "circle" function circle(){ } circle.prototype.pi=3.14159
This is javascript object that helps function to inherit new properties and methods

Using the prototype object to add custom methods to objects
//First, create the custom object "circle" function circle(){ } circle.prototype.pi=3.14159 // create the object method.
function alertmessage(){ alert(this.pi) } circle.prototype.alertpi=alertmessage

Example 1-Extending functionality to the pre-built string() object
<script type="text/javascript"> /*code for extending String object with method that writes text backwards*/
//core custom method for writing text backwards
function outputbackwards(){ for (i=this.length-1;i>=0;i--) document.write(this.charAt(i))
}
/Attach custom method to string object String.prototype.writeback=outputbackwards
var message1="Welcome to my site!"
message1.writeback()
var message2="Today is a beautiful day"
message2.writeback()
</script>
Output:
!etis ym ot emocleW yad lufituaeb a si yadoT

Example 2 Extending functionality to a custom JavaScript object
<script type="text/javascript"> //create dummy object function dummy(){ } //Create custom property function dummyproperty(){ } //Create custom method function dummymethod(){ } dummy.prototype.prop=dummyproperty dummy.prototype.method=dummymethod
</script>

Javascript Oop

by mussawir20

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