从自定义元素中删除 is="" 属性的预期行为是什么？

Question

例如，

假设我们有 <div is="awesomebutton"></div> 和一个自定义元素定义：

document.registerElement('awesomebutton', AwesomeButton)

删除 is="" 属性或用新值替换时的预期行为是什么？

Answer 1

Per section 7 of the latest Working Draft specification (26 February 2016)，应该对元素的类型没有影响：

After a custom element is instantiated, changing the value of the is attribute must not affect this element's custom element type.

然而 attributeChangedCallback 仍应正常触发。（规范并未免除 is 属性触发它。）您可以在支持的浏览器（Chrome 或设置了 dom.webcomponents.enabled 配置标志的 Firefox 中观察到该行为：

'use strict';

const prototype = Object.create(HTMLElement.prototype);
prototype.attributeChangedCallback = function(name, oldValue, newValue) {
  this.textContent = `my "${name}" attribute changed to "${newValue}"!`; 
};

document.registerElement('examp-el', {prototype: prototype, extends: 'div'});

const el = document.createElement('div', 'examp-el');
el.textContent = "I'm an element!";

document.body.appendChild(el);
el.setAttribute('is', "changed once");
el.removeAttribute('is');
el.setAttribute('is', "changed twice");
el.setAttribute('is', "changed thrice");

此规范尚未标准化，即将发生重大变化，但我不希望这种行为发生变化。它仍然由 Section 2.3 of the latest version of the Editor's Draft (currently 17 March 2016):

指定

After a custom element is created, changing the value of the is attribute does not change the element's behavior.

从自定义元素中删除 is="" 属性的预期行为是什么？

What is the expected behavior of removing the is="" attribute from Custom Element?

javascript

html

polymer

web-component

custom-element