如何使用Polymer查询元素DOM的Selector元素 [英] How to querySelector elements of an element's DOM using Polymer

问题描述

我有我的元素:

<dom-module id="x-el">
  <p class="special-paragraph">first paragraph</p>
  <content></content>
</dom-module>

我像这样使用它

<x-el>
  <p class="special-paragraph">second paragraph</p>
</x-el>

在我的当务之急:

Polymer({
  is: 'x-el',

  ready: function () {
    /* this will select all .special-paragraph in the light DOM
       e.g. 'second paragraph' */
    Polymer.dom(this).querySelectorAll('.special-paragraph');

    /* this will select all .special-paragraph in the local DOM
       e.g. 'first paragraph' */
    Polymer.dom(this.root).querySelectorAll('.special-paragraph');

    /* how can I select all .special-paragraph in both light DOM and
       local DOM ? */
  }
});

是否可以使用Polymer内置的做到这一点? 还是应该使用默认的DOM API?

Is it possible to do that using Polymer built-in's ? Or should I use the default DOM api ?

推荐答案

Polymer不会不提供帮助功能或抽象功能，该功能或抽象功能会从本地和列出节点DOM.

Polymer does not provide a helper function or abstraction that will list nodes both from the light and local DOMs.

如果需要此功能，则可以使用this.querySelector(selector).

If you require this functionality, you can use this.querySelector(selector).

另一方面，除了Polymer.dom(this.root).querySelectorAll(selector)方法之外，Polymer还提供了$$实用程序功能，该功能有助于访问元素的本地DOM的成员.该功能的用法如下:

On a side note, aside from the Polymer.dom(this.root).querySelectorAll(selector) method, Polymer also provides the $$ utility function which helps in accessing members of an element's local DOM. This function is used as follows:

<dom-module id="my-element">
  <template>
    <p class="special-paragraph">...</p>
    <content></content>
  </template>
</dom-module>

<script>
  Polymer({
    is: 'my-element',
    ready: {
      this.$$('.special-paragraph'); // Will return the <p> in the local DOM
    }
  });
</script>

请注意，与querySelectorAll不同，$$函数仅返回一个元素:本地DOM中与选择器匹配的 first 元素.

Note that, unlike querySelectorAll, the $$ function only returns one element: the first element in the local DOM which matches the selector.

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