是否每个ECMAScript运行时都在等待thenable? [英] Does every ECMAScript runtime with await await any Thenable?

问题描述

以下当前在节点，chrome，firefox中记录Yahtzee.

The following currently logs Yahtzee in node, chrome, firefox.

如您所见，甚至没有设置Promise的原型.

As you can see, not even prototype of Promise was set.

const fake = new Number(1)
fake.then = fn => setTimeout(fn, 0, 'Yahtzee')
const main = async () => {
  console.log(await fake)
}
main()

这是否通用? 更重要的是，这种行为可能会持续吗?

Does this works universally? And more importantly, will this behavior likely persist?

推荐答案

是的，这将起作用. 根据规范，将调用一个新的Promise并使用该值进行解析. Promise.resolve与thenable一起使用，因此对await

Yes, this will work. According to the specs, a new Promise will be called and resolve with that value. Promise.resolve works with thenable so it will work the same for await

所以，以上等同于

const fake = new Number(1)
fake.then = fn => setTimeout(fn, 0, 'Yahtzee')
const main = async () => {
  console.log(await Promise.resolve(fake))
}
main()

在 .resolve()在对象上调用then 的方法.

Where it is the .resolve() method that calls then on the object.

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