extendTag在Dart自定义元素 [英] extendTag in Dart custom element

问题描述

来自 javascript中的此链接，海关元素扩展按钮是作为：

from this link in javascript, customs element extending button is made as:

var MegaButton = document.registerElement('mega-button', {
  prototype: Object.create(HTMLButtonElement.prototype),
  extends: 'button'
});

<button is="mega-button">

我使用dart尝试使用dart，通过此代码：

I tried making the same using dart, by this code:

class MegaButton extends ButtonElement  {
static final tag = 'mega-button';
factory MegaButton()=>new Element.tag('button', tag);  
   MegaButton.created() : super.created() { 
       var shadow = this.createShadowRoot();
       shadow.text='save';
  }
}
 document.registerElement(MegaButton.tag, MegaButton);

    <button  is="mega-button"></button>
    <mega-button>click me</mega-button>

但出现此错误：

Exception: Unsupported operation: Class must provide extendsTag if base native class is not HTMLElement

任何帮助。感谢

推荐答案

document.registerElement应如下所示：

document.registerElement should look like:

document.registerElement(MegaButton.tag, MegaButton, extendsTag: 'button');

=> new Element.tag('button', tag);

另请参阅自定义聚合物元素在Dart中扩展AElement

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