如果不使用 Promise 对象的 then 方法，是否不可能从 Promise 对象中获取 [[PromiseValue]] ? [英] Is it impossible to get the [[PromiseValue]] from a Promise object without using the Promise object's then method?

问题描述

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Promises/A+ 规范2" rel="nofollow noreferrer">point-2 状态

The Promises/A+ specification at point-2 states

promise 表示异步操作的最终结果手术.与 promise 交互的主要方式是通过它的 then 方法，它注册回调以接收承诺的最终价值或承诺不能成为的原因完成.

A promise represents the eventual result of an asynchronous operation. The primary way of interacting with a promise is through its then method, which registers callbacks to receive either a promise’s eventual value or the reason why the promise cannot be fulfilled.

在对此问题的评论Promise 的返回值 OP 询问

是的，但这并没有从承诺中取出价值，或者应该我承认这在浏览器中是不可能的?

Right, but does not that take the value out of the promise, or should I accept that this is impossible from the browser?

回复的内容

不愿说明什么是不可能".

Hesitant to state what is "impossible".

随后提供了规范的链接，承诺，你错过了承诺点.

followed by providing links to the specification, Promises, You're Missing the Point of Promises.

是否不可能从Promise 对象中获取[[PromiseValue]]，除了在console.log(promiseObject)，而不使用Promise 对象的then 方法?

Is it impossible to get the [[PromiseValue]] from a Promise object, other than viewing the property value of the object at console.log(promiseObject), without using the Promise object's then method?

推荐答案

在 ES7 中不可行.promise 的值存储在 [[PromiseResult]] 内部槽:

Not possible in ES7. The value of a promise is stored in the [[PromiseResult]] internal slot:

承诺已被履行或拒绝的价值，如果任何.仅当 [[PromiseState]] 不是 "pending" 时才有意义.

The value with which the promise has been fulfilled or rejected, if any. Only meaningful if [[PromiseState]] is not "pending".

该插槽仅在 PerformPromiseThen 中读取抽象操作，仅通过 公开Promise.prototype.then.

That slot is only read in the PerformPromiseThen abstract operation, which is only exposed via Promise.prototype.then.

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