Instance...[Solved]

[eTianbun]

Is it possible to create an Instance of another Instance of an Object?ex:

//create an instance of Object-->a=new Object();a.name="Ben";//create an instance of a>-->b=new a;alert(b.name) 

Is it posible to do this? will object b, inherit the property from object A?

[Ingolme]

a needs to be a function, and any predefined values need to be inside the function:

var a = function() {  this.name = "Ben";} var b = new a();alert(b.name);

[eTianbun]

That means, its impossible to create an instance of an existing Object except it is a function. Ok, thanks for the info.

[Ingolme]

If you want to clone an object, you'll have to loop through all the object's properties using a for...in loop and assign the values to the new object's properties.

[eTianbun]

hmmm! :-\

var a=new Object();a.name="Ben";a.age=undefined;var b=new Object();pPos=0;for(properties in {b[pPos]=properties; pPos++}

you mean something like that? But that will be an array wright? Sorry if my code is incorrect, i usualy use mobile device(s) to access the NET, so i dont normaly test (debug), before i post! EDIT: By-the-way, if the object have a method, what will happen? Will the for...in execute it?

[Ingolme]

No, methods won't be executed. Everything in the for...in loop is treated as a reference (which also means that arrays and objects inside the object won't be cloned, just referenced)

var a = new Object();a.name = "Ben";a.age = 20; var b = new object();for(propertyName in a) {  if( !(propertyName in Object.prototype) ) {    b[propertyName] = a[propertyName];  }}

[eTianbun]

Kinda confusing! I see a condiction statement in the for...in.

[Ingolme]

Kinda confusing! I see a condiction statement in the for...in. Can you write a short note on vat? I dont realy understand that part!

Yeah, I should have explained that. The object has a series of properties that are read-only or are set by the browser, like the "constructor" property, so when copying properties, you need to make sure that the property isn't part of the object's prototype.

[eTianbun]

oook! That means, the constructor property is defined inside the prototype function in all function wright? In your code, it seems the propertyName, is going to be the same as the value.

Ben='Ben'

am i currect?

[Ingolme]

No. There are two ways to get a property's value: a.name or a["name"] The second one allows you to dynamically access properties:

var propertyName = "name";alert(a[propertyName]) // This displays the value of a.name

When copying an object, you copy the value of a property to the property of the same name:

b.name = a.name; OR b["name"] = a["name"] OR var propertyName = "name";b[propertyName] = a[propertyName]

[eTianbun]

oopse, my bad! I forgot that the for..in loop refrence the object's property name and not extracting the property's value. Thanks bro, i got that!