具有对象类型属性的Lit元素

Question

如何使用具有Object-type属性的Lit-element？我认为定义myelement有效：

static get properties() {
    return {
        whales:Object
    }
}
constructor() {
    super();
    this.whales={"nb":0};
}

html，这也有效：

       <my-element id="mytest" whales='{"nb":2}'></my-element>

但我不能让setAttribute工作：

myElement.setAttribute("whales", {"nb":4});

编辑：谢谢你mishu，你的回答帮助我解决了我的问题。如果有人想知道，这是完整的工作示例。但是仍有一件事我无法工作：如果值是一个对象（对象被处理为字符串），我不知道如何以声明方式给出属性初始值。

index.html的：

    <!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Lit-html test</title>
</head>
<body>
  <script type="module" src="./components/my-e.js"></script>

  <button id="reset" onclick="reset()">reset</button>
  <p>1 works: <my-e id="mytest"></my-e></p>
  <p>2 doesn't work: <my-e id="mytest2" person='{"name":"Joe", "age":32}'></my-e></p>
  <script src="main.js"></script>
</body>
</html>

main.js：

     function updatePerson(e) {
  var myE = e.target;
  myE.person = e.detail;
  myE._requestRender();
}
function reset() {
  var p = { "name": "Jack", "age": 20 };
  var myE = document.getElementById('mytest');
  myE.person = p;
  myE._requestRender();

  myE = document.getElementById('mytest2');
  myE.person = p;
  myE._requestRender();
}
document.getElementById('mytest').addEventListener('person', updatePerson);
document.getElementById('mytest2').addEventListener('person', updatePerson);

我-e.js：

import { LitElement, html } from './lit-element.js';
class MyE extends LitElement {
  static get properties() {
    return {
      person: Object
    }
  }
  constructor() {
    super();
    this.person = { "name": "Paul", "age": 40 };
    this.addEventListener('click', async (e) => {
      await this.renderComplete;
      var p = {};
      p.name = this.person.name + ", a";
      p.age = this.person.age + 1;
      this.dispatchEvent(new CustomEvent('person', { detail: p }))
    });
  }
  _render({ person }) {
    return html`
         <p> Name: ${person.name}</p>
         <p>Age: ${person.age}</p>
    `;
  }
}
customElements.define('my-e', MyE);

Answer 1

另一答案