javascript - 为什么 Ember 观察者不对数组开火？

Question

我正在尝试监听数组中每个元素的特定属性并从中获取结果。但是，更新似乎没有正确发生。

var emptyEmberObjectClass = Ember.Object.extend({});
var container = Ember.Object.extend({
  data: Ember.A([
    emptyEmberObjectClass.create({yo:1}),
    emptyEmberObjectClass.create({yo:2}),
    emptyEmberObjectClass.create({yo:3})
  ]),
  computedData: Ember.computed('data.@each.yo', function(){
    var sum = 0;
    this.get('data').forEach(function(data){
      sum = sum + data.yo;
    });
    return sum;
  }),
  test: Ember.observer('computedData', function(){
    Ember.$('#a').html('woohoO!');
  })
}).create();
var existingItem = container.get('data');
existingItem.objectAt(0).set('yo', 50);

http://jsfiddle.net/stb0nr2y/1/

如您所见，文本字段仍然显示“开始”并且没有更新为“woohoO!”。

任何帮助将不胜感激。

Answer 1

JavaScript:

var emptyEmberObjectClass = Ember.Object.extend({});
var container = Ember.Object.extend({
  data: Ember.A([
    emptyEmberObjectClass.create({yo:1}),
    emptyEmberObjectClass.create({yo:2}),
    emptyEmberObjectClass.create({yo:3})
  ]),
  computedData: Ember.computed('data.@each.yo', function(){
    var sum = 0;
    this.get('data').forEach(function(data){
      sum += data.get('yo');
    });
    return sum;
  }),
  testObs: Ember.on('init', Ember.observer('computedData', function() {
    Ember.$('#a').html('woohoO! cd: `' + this.get('computedData') + '`');
  }))
}).create();

var existingItem = container.get('data');
var target = existingItem.objectAt(0);
target.set('yo', 50);

target.set('yo', 100);

正确更新 DOM:

woohoO! cd: 55

然后:

woohoO! cd: 105

请注意，我使用的是 Ember v1.13.10:

<script src="http://builds.emberjs.com/tags/v1.13.10/ember.min.js"></script>

Working demo.