ExtJS 3：创建自定义类的两种方式：有什么区别？ [英] ExtJS 3: Two ways of creating custom class: what's the difference?

问题描述

我正在尝试学习ExtJS和面向对象的JavaScript。我已经看到人们以几种方式在自定义命名空间中定义类。这两种方法有什么区别？

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?

方法1

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

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

方法2

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

方法2更容易阅读，需要较少的代码;有没有什么方法1更好？谢谢！

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

推荐答案

基本上是一样的，除了你可以在第一种方法的self-exectuing函数中使用私有变量，而您只能在第二个定义全局变量。

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.

例如：

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 );

所以，第一种方法是非常有用的，如果你使用一个变量，你不会

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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