打字稿承诺拒绝类型 [英] Typescript Promise rejection type

问题描述

如何设置拒绝我的承诺的类型?假设我愿意:

How do I set the type of the rejection of my promise? Let's say I do:

const start = (): Promise<string> => {
   return new Promise((resolve, reject) => {
      if (someCondition) {
         resolve('correct!');
      } else {
         reject(-1);
      }
   });
}

假设我想用一个数字拒绝.但是我不能设置类型；我可以将任何我想要的传递给 reject 在这里.

Let's say I want to reject with a number. But I cannot set the type; I can pass whatever I want to the reject here.

而且，在使用这个promise的时候，如果我错误地使用了拒绝响应类型，我希望有编译错误.

Moreover, when using this promise, I want to have compiling error if I use the rejection response type incorrectly.

推荐答案

如 this issue, Promise 对于已完成和被拒绝的承诺没有不同的类型.拒绝 接受不影响承诺类型的任何参数.

As explained in this issue, Promise doesn't have different types for fulfilled and rejected promises. reject accepts any argument that doesn't affect type of a promise.

目前 Promise 不能更好地输入.这是因为可以通过在 then 或 catch 中 throwing 来拒绝承诺(这是拒绝现有承诺的更好方法), 这不能通过打字系统来处理；此外，除了never之外，TypeScript 也没有特定于异常的类型.

Currently Promise cannot be typed any better. This results from the fact that a promise can be rejected by throwing inside then or catch (this is a preferable way to reject existing promise), and this cannot be handled by typing system; also, TypeScript also doesn't have exception-specific types except never.

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