定义一个元素

文档： 1.x - > 2.x 升级指南 ，注册元素 ，共享样式模块 。

<link rel="import" href="bower_components/polymer/polymer-element.html">
<dom-module id="element-name">
  <template>
    <!-- Use one of these style declarations, but not both -->
    <!-- Use this if you don’t want to include a shared style -->
    <style></style>
    <!-- Use this if you want to include a shared style -->
    <style include="some-style-module-name"></style>
  </template>
  <script>
    class MyElement extends Polymer.Element {
      static get is() { return 'element-name'; }
      // All of these are optional. Only keep the ones you need.
      static get properties() { ... }
      static get observers() { ... }
    }

    // Associate the new class with an element name
    customElements.define(MyElement.is, MyElement);
  </script>
</dom-module>

要获取特定自定义标记的类定义，可以使用 customElements.get('element-name')。