Disallow async functions which have no await expression (require-await)

禁止使用不带 await 表达式的 async 函数 (require-await)

Asynchronous functions in JavaScript behave differently than other functions in two important ways:

JavaScript 中的异步函数与其他函数在两个重要方面表现不同:

  1. The return value is always a Promise.
  2. 返回值总是一个 Promise。
  3. You can use the await operator inside of them.
  4. 你可以使用其中的 await 操作符。

The primary reason to use asynchronous functions is typically to use the await operator, such as this:

使用异步函数的主要原因通常是使用 await 操作符，例如:

async function fetchData(processDataItem) {
    const response = await fetch(DATA_URL);
    const data = await response.json();

    return data.map(processDataItem);
}

Asynchronous functions that don’t use await might not need to be asynchronous functions and could be the unintentional result of refactoring.

不使用 await 的异步函数可能不需要是异步函数，也可能是重构的意外结果。

Rule Details

This rule warns async functions which have no await expression.

该规则对不包含 await 表达式的 async 函数发出警告。

Examples of incorrect code for this rule:

错误 代码示例：

/*eslint require-await: "error"*/

async function foo() {
    doSomething();
}

bar(async () => {
    doSomething();
});

Examples of correct code for this rule:

正确 代码示例：

/*eslint require-await: "error"*/

async function foo() {
    await doSomething();
}

bar(async () => {
    await doSomething();
});

function foo() {
    doSomething();
}

bar(() => {
    doSomething();
});

// Allow empty functions.
async function noop() {}

When Not To Use It

Asynchronous functions are designed to work with promises such that throwing an error will cause a promise’s rejection handler (such as catch()) to be called. For example:

异步函数被设计用来处理 Promise ，这样抛出错误将导致调用 Promise 的拒绝处理程序(如 catch() )。例如:

async function fail() {
    throw new Error("Failure!");
}

fail().catch(error => {
    console.log(error.message);
});

In this case, the fail() function throws an error that is intended to be caught by the catch() handler assigned later. Converting the fail() function into a synchronous function would require the call to fail() to be refactored to use a try-catch statement instead of a promise.

在本例中，fail() 函数抛出一个错误，该错误将被稍后分配的 catch() 处理程序捕获。将 fail() 函数转换为同步函数需要对 fail() 调用进行重构，以使用 try-catch 语句而不是 promise。

If you are throwing an error inside of an asynchronous function for this purpose, then you may want to disable this rule.

如果为此目的在异步函数中抛出错误，则可能需要禁用此规则。

Version

This rule was introduced in ESLint 3.11.0.

该规则在 ESLint 3.11.0 中被引入。

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