Adding Methods and Data to an Object Prototype

You can write code that adds methods and data to an object prototype at any time. You must define the object class but you do not have to create an instance of the object before you assign prototype values to it. If you assign a method or data to an object prototype, then Siebel CRM updates every instance of that object to include the prototype.

If you attempt to write to a property that Siebel CRM assigns through a prototype, then it creates a new variable for the newly assigned value. It uses this value for the value of this instance of the object property. Other instances of the object still refer to the prototype for their values. The following example specifies joe as a special rectangle whose area is equal to three times the width plus half the height:

function joe_area()
{
   return (this.width * 3) + (this.height/2);
}
joe.area = joe_area;

This code creates a value for joe.area that supersedes the prototype value. In this example, this value is a function. The sally.area property is still the default value that this prototype defines. The joe instance uses the new definition for the area method.

You cannot write code that declares a prototype in a function scope.