polymer - 我如何使用 :first-child selector w/shadow DOM's element?

Question

我想从自定义元素的内容中提取第一段(作为摘要)。我希望以下内容起作用:

<polymer-element name="x-thing" noscript>
  <template>
    <segment class="summary">
      <content select="p:first-child"></content>
    </segment>
    <segment>
      <content></content>
    </segment>
  </template>
</polymer-element>

不幸的是， <content select="p:first-child">似乎不匹配任何东西:(

Here's a corresponding codepen .

Answer 1

只有 :not() Shadow DOM 规范支持:http://w3c.github.io/webcomponents/spec/shadow/#dfn-matching-criteria

相关错误:http://crbug.com/343332