Question

我希望构建一个数据类型的行为来监听属性更新。听取儿童财产变化的最佳方式是什么？

function do_something_when_property_updates(property_name) {
  return {
    // How to listen to property?
    properties: {
       property_name: {
         // This behavior doesn't (and shouldn't) own the property
         observer: foo
       }
    },
    foo: function(value) {
      // Update handler
    }
  };
}

Polymer({
  is:'test-element', 
  properties: {
    bar: {
      type: Object
    }
  },
  behaviors: [do_something_when_property_updates('bar')]
});

Answer 1

使用observers:[]属性。 See the docs

function do_something_when_property_updates(property_name) {
  return {
    observers: [
      // Note .* will observe any changes to this object or sub-object
      'foo(' + property_name + '.*)'
    ],
    foo: function(value) {
      // Update handler
    }
  };
}

Polymer({
  is:'test-element', 
  properties: {
    bar: {
      type: Object
    }
  },
  behaviors: [do_something_when_property_updates('bar')],
  ready: function() {
    this.set('bar.a', {}); // foo() is invoked
    this.set('bar.a.b', true); // foo() is invoked
  }
});

聚合物行为听取儿童财产变化

1 个答案: