no-async-promise-executor

禁止使用异步函数作为 Promise 执行器

new Promise 构造函数接受一个执行器函数作为参数，该函数具有 resolve 和 reject 参数，可用于控制创建的 Promise 的状态。例如：

¥The new Promise constructor accepts an executor function as an argument, which has resolve and reject parameters that can be used to control the state of the created Promise. For example:

const result = new Promise(function executor(resolve, reject) {
  readFile('foo.txt', function(err, result) {
    if (err) {
      reject(err);
    } else {
      resolve(result);
    }
  });
});
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执行器函数也可以是 async function。但是，这通常是一个错误，原因如下：

¥The executor function can also be an async function. However, this is usually a mistake, for a few reasons:

• 如果异步执行器函数抛出错误，错误将丢失，不会导致新构建的 Promise 拒绝。这可能会使调试和处理一些错误变得困难。

  ¥If an async executor function throws an error, the error will be lost and won’t cause the newly-constructed Promise to reject. This could make it difficult to debug and handle some errors.

• 如果 Promise 执行器函数使用 await，这通常表明实际上不需要使用 new Promise 构造函数，或者可以缩小 new Promise 构造函数的范围。

  ¥If a Promise executor function is using await, this is usually a sign that it is not actually necessary to use the new Promise constructor, or the scope of the new Promise constructor can be reduced.

规则详情

¥Rule Details

此规则旨在禁止异步 Promise 执行器功能。

¥This rule aims to disallow async Promise executor functions.

此规则的错误代码示例：

¥Examples of incorrect code for this rule:

/*eslint no-async-promise-executor: "error"*/

const foo = new Promise(async (resolve, reject) => {
  readFile('foo.txt', function(err, result) {
    if (err) {
      reject(err);
    } else {
      resolve(result);
    }
  });
});

const result = new Promise(async (resolve, reject) => {
  resolve(await foo);
});
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此规则的正确代码示例：

¥Examples of correct code for this rule:

/*eslint no-async-promise-executor: "error"*/

const foo = new Promise((resolve, reject) => {
  readFile('foo.txt', function(err, result) {
    if (err) {
      reject(err);
    } else {
      resolve(result);
    }
  });
});

const result = Promise.resolve(foo);
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何时不使用

¥When Not To Use It

如果你的代码库不支持异步函数语法，则无需启用此规则。

¥If your codebase doesn’t support async function syntax, there’s no need to enable this rule.

版本

此规则是在 ESLint v5.3.0 中引入。

资源

• 规则源码
• 测试源码