is polymorphism supported by javascript

[newlearner]

Hi,
does javascript support polymorphism (OOPS Concepts). if yes can some body eplain it or give a sample.

looking forward for a earliest reply...

Thanks in advance

[gits]

hi ...

of course ;) ... have a look at the following example:

// constructor of a parent class
function PARENT_CLASS() {
}
 
// a method of the parent class
PARENT_CLASS.prototype.a_method = function() {
    // do something
}
 
// an other method of the parent class
PARENT_CLASS.prototype.b_method = function() {
    // do something
}
 
// constructor of a child class
function CHILD_CLASS_A() {
}
 
// inheriting from parent class
CHILD_CLASS_A.prototype = new PARENT_CLASS;
 
// fixing the constructor - otherwise the instance later on would 
// be of type PARENT_CLASS
CHILD_CLASS_A.prototype.constructor = CHILD_CLASS_A;
 
// override the inherited method now and we have simple polymorphism
CHILD_CLASS_A.prototype.a_method = function() {
    // do something other for the child class here
}
 
// now the usage :)
 
var pcl = new PARENT_CLASS;
pcl.a_method(); // initial behaviour
pcl.b_mehtod(); // initial behaviour
 
var ccl = new CHILD_CLASS_A;
ccl.a_method(); // overridden behaviour
ccl.b_method(); // initial behaviour
 

kind regards

[mrhoo]

gits, I believe your line 20-
CHILD_CLASS_A.prototype = PARENT_CLASS
should be
CHILD_CLASS_A.prototype =new PARENT_CLASS;
to prevent the child class from overwriting the parent's prototype with its methods.

[gits]

gits, I believe your line 20-
CHILD_CLASS_A.prototype = PARENT_CLASS
should be
CHILD_CLASS_A.prototype =new PARENT_CLASS;
to prevent the child class from overwriting the parent's prototype with its methods.

thanks ... of course it is a typo ... i'll edit the code ...

kind regards

[newlearner]

thanks ... of course it is a typo ... i'll edit the code ...

kind regards

tnx..
I have a doubt though.. is function overloading supported....
also i feel polymorphism (overridding) is supported only thru inheritance can two functions of the same name be found inside a base class..

Looking forward for your comments....

Thanks in advance for your reply.

[pbmods]

Heya, New Learner.

Just like you can do this:

var $obj1 ={a: 1, b: 2};
var $obj2 = new Object($obj1);
$obj2.a = 5;
 
alert(print_r($obj1));  // alerts 'Array ( [a] => (Number) 1, [b] => (Number) 2 )'
alert(print_r($obj2));  // alerts 'Array ( [a] => (Number) 5, [b] => (Number) 2 )'
 

to overload a data member of an object, so can you overload a function.

Remember: functions are objects themselves in JavaScript! For more information, check out this article.

print_r() is available here.