javascript - 函数类正确使用的property()方法

Question

文档中的示例:

App.Person = Ember.Object.extend({
  // these will be supplied by `create`
  firstName: null,
  lastName: null,

  fullName: function() {
    return this.get('firstName') + ' ' + this.get('lastName');
  }.property('firstName', 'lastName')
});

var ironMan = App.Person.create({
  firstName: "Tony",
  lastName:  "Stark"
});

ironMan.get('fullName') // "Tony Stark"

我不明白为什么我必须指定像 .property('firstName', 'lastName') 这样的依赖项，如果我已经指出需要返回什么:return this.get(' firstName') + ' ' + this.get('lastName') 上面的示例可以在没有它的情况下工作(只需使用 property())。谢谢。

Answer 1

用于缓存。

来自 docs :

By default the function backing the computed property will only be called once and the result will be cached. You can specify various properties that your computed property is dependent on. This will force the cached result to be recomputed if the dependencies are modified.