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Dynamically creating a new javascript class from an existing object

Asked 2010-02-26T15:03:10.567
18

Say I have the following code:

var album = new MyObject('album');

Assume that when the object is constructed, a bunch of properties relative to only albums are loaded via AJAX. Would it be possible to create an Album class so that at a later point, I may just do this:

var anotherAlbum = new Album();

The Album constructor would automatically set the properties that are unique to album objects, based on what was loaded when creating MyObject('album')

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12

JavaScript is prototypal, not classical, so if you think in terms of classes, you're doing it wrong.

You don't have to use the new operator at all. You can create a new object using the object literal:

var myObject = {attr1: 'val1', attr2: 'val2'};

Then you can create a new instance of that object:

var mySecondObject = Object.create(myObject);

Now you can change the attributes of mySecondObject, and if it has methods you can overload them just as easily:

mySecondObject.attr1 = "Hello";

mySecondObject.attr2 = function() {
                           return "World!";
                       };

And then mySecondObject will of course have all the properties that you gave myObject at creation.

Be aware that this is a simple version, and that this leaves all attributes 'public'. If you need some privacy, it can be achieved by adding some functions to the mix. It's a bit more complicated though, so let me know if you're interested...

answered 2010-02-26T15:40:59.343

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