ember.js中'[]'属性和'@each'属性有什么区别？ [英] What is the difference between the '[]' property and the '@each' property in ember.js?

问题描述

我注意到，可枚举的mixin已经计算出取决于'[]'属性的属性，而ember数组也有 @each'属性

根据'[]'有什么区别？和'@ each'？

我的模糊的理解（如果我错了，纠正我）是'[]'阵列内容被替换。但这是不同的，取决于物业本身？

考虑以下类：

  C = Ember.Object .extend（{
 something：null，
 watcher1：（function（）{
 console.log（'watcher1'）
}）。observes（'things。[] ）
 watcher2：（function（）{
 console.log（'watcher2'）
}）。观察（'something。@ each'）
}）; 
  

我创建一个如下实例：

  c = C.create（{things：Ember.A（['a'，'b']）}）; 
  

以下内容：

  c.get（'things'）。replace（0，1，['z']）
  

触发器 watcher1 和 watcher2

和以下内容：

  c.get（'things'）。setObjects（['1'，'2']） 
  

还触发 watcher1 和 watcher2

如下：

  c.get（'something'）。addObject（'v'）
  

那么有没有区别？我们什么时候应该使用一个对另一个？

谢谢！
Kevin

解决方案

使用 @each if您需要观察数组元素的属性

@each 支持观察内部元素的属性阵列。例如， people。@ each.name 。括号符号不支持这一点。这是一个 jsbin演示。

@each 是一个 Array实例的属性，返回一个 EachProxy 实例。另一方面， [] 只是返回这个 。

使用 [] 如果您需要它在非数组枚举上工作

根据ember更改日志，括号符号被废止，以支持 @each 在ember 0.9.4 ，但在 0.9.8 。 重新启用它的提交表示 [] 可以用于非数组枚举，例如 Ember.Set 实例。 jsbin演示。

I've noticed that the enumerable mixin has computed properties that depends on the '[]' property, while ember arrays also have the '@each' property.

What is the difference between depending on '[]' and '@each'?

My vague understanding (correct me if I'm wrong) is that '[]' is triggered when the array content is replaced. But is this different than depending on the property itself?

Consider the the following class:

C = Ember.Object.extend({
  things: null,
  watcher1: (function() {
    console.log('watcher1')
  }).observes('things.[]'),
  watcher2: (function() {
    console.log('watcher2')
  }).observes('things.@each')
});

And I create an instance as follows:

c = C.create({things: Ember.A(['a', 'b'])});

The following:

c.get('things').replace(0, 1, ['z'])

triggers watcher1 and watcher2

And the following:

c.get('things').setObjects(['1', '2'])

also triggers watcher1 and watcher2

As does:

c.get('things').addObject('v')

So is there any difference? When should we use one vs. the other?

Thanks! Kevin

解决方案

Use @each if you need to observe properties of array elements

@each supports observing properties of the elements inside the array. For example, [e-mail]. The bracket notation does not support this. Here is a jsbin demo.

@each is a property of Array instances that returns an EachProxy instance that handles the delegation. On the other hand, [] simply returns this.

Use [] if you need it to work on non-Array enumerables

According to the ember changelog, the bracket notation was made defunct in favor of @each in ember 0.9.4, but then re-enabled in 0.9.8. The commit that re-enables it indicates that [] can be used for non-Array enumerables such as Ember.Set instances. jsbin demo.

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