ExtJS 3: Two ways of creating custom class: what's the difference?

javascript extjs extjs3
Clint Harris picture Clint Harris · Nov 7, 2010 · Viewed 9.2k times · Source

I'm trying to learn ExtJS and object-oriented JavaScript in general. I've seen people defining classes in custom namespaces in a couple of ways. What's the difference between these two methods?

Method 1

Ext.ns('myapp.cars');
(function(){
    var Car = Ext.extend(Object, {
       //...
    })

    myapp.cars.Car = Car;
})()

Method 2

Ext.ns('myapp.cars');
myapp.cars.Car = Ext.extend(Object, {
       //...
});

Method 2 is easier to read and requires less code; is there any reason Method 1 is better? Thanks!

Answer

Harmen picture Harmen · Nov 7, 2010

It's basically the same, except that you could use private variables in the self-exectuing function of the first method, while you can only define global variables in the second one.

For example:

Ext.ns('myapp.cars');
(function(){

    var carInfo = {
      goodEngine: true
    };

    var Car = Ext.extend(Object, {
       info: carInfo
    });

    myapp.cars.Car = Car;
})()

// carInfo is undefined here, so this will give an error
alert( carInfo.goodEngine );

So, the first method is quite useful if you work with a bunge of variables that you won't use later on.

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