如何使用带有阴影DOM的< content>的:first-child选择器元素? [英] How can I use the :first-child selector w/ shadow DOM's <content> element?

问题描述

我想从自定义元素的内容中提取第一段(作为摘要).我希望以下方法能起作用:

I'd like to extract the first paragraph from a custom element's content (as a summary). I would expect the following to work:

<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">似乎与任何内容都不匹配:(

Unfortunately, the <content select="p:first-child"> doesn't appear to match anything :(

这是相应的codepen .

推荐答案

Shadow DOM规范仅支持:not():

Only :not() is supported in the Shadow DOM spec: http://w3c.github.io/webcomponents/spec/shadow/#dfn-matching-criteria

相关错误: http://crbug.com/343332

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