最接近异步构造函数的方法是等待它完成执行，如果它还没有在它的所有方法中执行:

class SomeClass {
    constructor() {
        this.asyncConstructor = (async () => {
            // Perform asynchronous operations here
        })()
    }

    async someMethod() {
        await this.asyncConstructor
        // Perform normal logic here
    }
}

我通常更喜欢返回一个新实例的静态异步方法，但这里有另一种方法。它更接近于字面上的等待构造函数。它与TypeScript一起工作。

class Foo {
  #promiseReady;

  constructor() {
    this.#promiseReady = this.#init();
  }

  async #init() {
    await someAsyncStuff();
    return this;

  }

  ready() {
    return this.promiseReady;
  }
}

let foo = await new Foo().ready();

这是可以做到的。 一个简单的代码:

class test
{
   constructor ()
   {
      return new Promise ( (resolve, reject) => { resolve(this); });
   }
   doHello() {console.log("hello");}
}
async function main()
{
   let t = await new test(); //invoking synchronously
   t.doHello(); //t is not a pormise
}
main();

或与上面相同，但添加了实际延迟，使用setTimeout

class test
{
   constructor ()
   {
      return new Promise ( (resolve, reject) =>
      {
         setTimeout (resolve, 5, this);
      });
   }
   doHello() {console.log("hello");}
}
async function main()
{  
   let t = new test(); //now t is a promise
   t.then((a)=>{ a.doHello();}); //a is the real reference to test instance
   console.log("testing"); //"testing" will be printed 5 seconds before "hello"
}
main();

这里是我在现实生活中的一段代码，使用异步图像加载:

class HeightMap extends GlVAObject
{
   #vertices = [];
   constructor (src, crossOrigin = "")
   {
      //super(theContextSetup);
      let image = new Image();
      image.src = src;
      image.crossOrigin = crossOrigin;
      return new Promise ( (resolve, reject) =>
         {
            image.addEventListener('load',  () =>
            {
               //reading pixel values from image into this.#vertices
               //and generate a heights map
               //...
               resolve(this);
            } );
         });
   }
///...
}
async function main()
{
   let vao = await new HeightMap ("./heightmaps/ArisonaCraterHeightMap.png");
///...
}
main();

您应该将该函数添加到实例中。Promise将它识别为Promise的可支持对象。解决自动

const asyncSymbol = Symbol();
class MyClass {
    constructor() {
        this.asyncData = null
    }
    then(resolve, reject) {
        return (this[asyncSymbol] = this[asyncSymbol] || new Promise((innerResolve, innerReject) => {
            this.asyncData = { a: 1 }
            setTimeout(() => innerResolve(this.asyncData), 3000)
        })).then(resolve, reject)
    }
}

async function wait() {
    const asyncData = await new MyClass();
    alert('run 3s later')
    alert(asyncData.a)
}

其他答案都忽略了一个显而易见的事实。简单地从你的构造函数调用一个async函数:

constructor() {
    setContentAsync();
}

async setContentAsync() {
    let uid = this.getAttribute('data-uid')
    let message = await grabUID(uid)

    const shadowRoot = this.attachShadow({mode: 'open'})
    shadowRoot.innerHTML = `
      <div id="email">A random email message has appeared. ${message}</div>
    `
}

您可以立即调用一个返回消息的匿名异步函数，并将其设置为message变量。如果您不熟悉这种模式，您可能想看看立即调用的函数表达式(IEFES)。这将非常有效。

var message = (async function() { return await grabUID(uid) })()