Disabling Prototype Extensions

禁用基于原型的扩展

By default, Ember.js will extend the prototypes of native JavaScript objects in the following ways:

默认情况下，Ember.js 以下列方式对原生的JavaScript对象进行基于原型的扩展：

  • Array is extended to implement the Ember.Enumerable, Ember.MutableEnumerable, Ember.MutableArray and Ember.Array interfaces. This polyfills ECMAScript 5 array methods in browsers that do not implement them, adds convenience methods and properties to built-in arrays, and makes array mutations observable.
  • String is extended to add convenience methods, such as camelize() and fmt().

  • Function is extended with methods to annotate functions as computed properties, via the property() method, and as observers, via the observes() or observesBefore() methods.

  • Array被扩展用来实现Ember.Enumerable, Ember.MutableEnumerable, Ember.MutableArray 和 Ember.Array接口。此举填补了本来不支持 ECMAScript 5 数组方法的浏览器的空白，为数组增加了便捷方法和属性，同时使数据的变化可观察。

  • String被扩展了诸如camelize()和fmt()的便捷方法。
  • Function通过property()扩展了将函数注解为计算属性的方法，还扩展了将方程注解为观察者的方法，这些方法为observes()或observesBefore()。

This is the extent to which Ember.js enhances native prototypes. We have carefully weighed the tradeoffs involved with changing these prototypes, and recommend that most Ember.js developers use them. These extensions significantly reduce the amount of boilerplate code that must be typed.

这就是Ember.js增强原生原型的范围。我们仔细权衡了改变这些原型的利弊，因此推荐多数Ember.js开发者能使用这些扩展。这些扩展显著地减少了必须输入的样板文件代码量。

However, we understand that there are cases where your Ember.js application may be embedded in an environment beyond your control. The most common scenarios are when authoring third-party JavaScript that is embedded directly in other pages, or when transitioning an application piecemeal to a more modern Ember.js architecture.

然后，我们也理解有时你的Ember.js程序会嵌入到一个你不能控制的环境中。经常是将第三方JavaScript代码嵌入到其他页面中时，或是当将应用一块一块地迁移到更先进的Ember.js架构中来的时候。

In those cases, where you can’t or don’t want to modify native prototypes, Ember.js allows you to completely disable the extensions described above.

那些情况下，你不能或不想修改原生的原型，Ember.js允许你彻底关闭上面所说的扩展。

To do so, simply set the EXTEND_PROTOTYPES flag to false:

只要将EXTEND_PROTOTYPES标志为设为false即可。

  1. window.ENV = {};
  2. ENV.EXTEND_PROTOTYPES = false;

Note that the above code must be evaluated before Ember.js loads. If you set the flag after the Ember.js JavaScript file has been evaluated, the native prototypes will already have been modified.

需要注意的是，上面的代码必须在Ember.js加载 之前 运行。如果你在Ember.js运行了之后再设置此标志位，那么原生的原型就已经被修改过了。

Life Without Prototype Extension

没有基于原型的扩展的情况

In order for your application to behave correctly, you will need to manually extend or create the objects that the native objects were creating before.

要想程序正常运作，你得手动扩展或创建对象，与之前创建对象的过程一样。

Arrays

数组

Native arrays will no longer implement the functionality needed to observe them. If you disable prototype extension and attempt to use native arrays with things like a template’s {{#each}} helper, Ember.js will have no way to detect changes to the array and the template will not update as the underlying array changes.

原生数组不再继续实现监控自身变化所需的功能。如果你关闭了基于原型的扩展并且试图在模板的{{#each}}等助手方法中使用原生数组的话，Ember.js就没办法检测到数组的内容变化，模板也不会随着数组的变化而自动更新。

Additionally, if you try to set the model of an Ember.ArrayController to a plain native array, it will raise an exception since it no longer implements the Ember.Array interface.

另外，你试图将Ember.ArrayController的模型设置为普通的原生数组时，Ember.js会报一个异常，因为原生数组已然不再继续实现Ember.Array接口了。

You can manually coerce a native array into an array that implements the required interfaces using the convenience method Ember.A:

当然你可以将原生数组强制转换成实现了必需接口的数组，只要你使用Ember.A这个便捷方法就可以了。

  1. var islands = ['Oahu', 'Kauai'];
  2. islands.contains('Oahu');
  3. //=> TypeError: Object Oahu,Kauai has no method 'contains'
  4. //=> 类型错误: Oahu,Kauai 对象没有 'contains' 方法
  6. // Convert `islands` to an array that implements the
  7. // Ember enumerable and array interfaces
  8. //将`islands`转换为实现了Ember枚举以及数组接口的数组
  9. Ember.A(islands);
  11. islands.contains('Oahu');
  12. //=> true

Strings

字符串

Strings will no longer have the convenience methods described in the Ember.String API reference.. Instead, you can use the similarly-named methods of the Ember.String object and pass the string to use as the first parameter:

字符串不再拥有Ember.String API reference.中描述的便捷方法。然而，你可以使用Ember.String对象中名称类似的方法并将字符串作为第一个参数传进来：

  1. "my_cool_class".camelize();
  2. //=> TypeError: Object my_cool_class has no method 'camelize'
  3. //=> 类型错误: my_cool_class 对象没有`camelize`方法
  5. Ember.String.camelize("my_cool_class");
  6. //=> "myCoolClass"

Functions

函数

To annotate computed properties, use the Ember.computed() method to wrap the function:

用Ember.computed()方法来包裹函数以标记计算属性。

  1. // This won't work:
  2. //这样的代码不会起作用：
  3. fullName: function() {
  4.   return this.get('firstName') + ' ' + this.get('lastName');
  5. }.property('firstName', 'lastName')
  8. // Instead, do this:
  9. //你需要这样做：
  10. fullName: Ember.computed('firstName', 'lastName', function() {
  11.   return this.get('firstName') + ' ' + this.get('lastName');
  12. })

Observers are annotated using Ember.observer():

用Ember.observer()来标记观察者：

  1. // This won't work:
  2. //这样的代码不会起作用：
  3. fullNameDidChange: function() {
  4.   console.log("Full name changed");
  5. }.observes('fullName')
  8. // Instead, do this:
  9. //你需要这样做：
  10. fullNameDidChange: Ember.observer('fullName', function() {
  11.   console.log("Full name changed");
  12. })