fix some translate error (#34138)

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Johnson
2019-02-10 14:06:59 +08:00
committed by Jingyi Ding
parent 320f4c3637
commit c47a7f0bf1

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---
title: Await Promises
localeTitle: 等待承诺
localeTitle: Await Promise
---
## 等待承诺
## Await Promise
`async` / `await` [运算符](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators)可以更轻松地实现许多异步Promise。它们还允许工程师编写更清晰,更简洁,可测试的代码。
`async` / `await` [关键字](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators)可以更轻松地实现许多异步Promise。它们能帮助工程师编写更清晰,更简洁,可测试的代码。
要理解这个主题,您应该对[Promise](https://guide.freecodecamp.org/javascript/promises)如何工作有充分的了解。
要理解这个主题,您需要对[Promise](https://guide.freecodecamp.org/javascript/promises)的工作机制有充分的了解。
* * *
## 基本语法
\`\`\`\`javascript function slowlyResolvedPromiseFuncstring{ 返回新的Promiseresolve => { setTimeout=> { 解析(字符串); }5000; }; }
```javascript
function slowlyResolvedPromiseFunc (string) {
return new Promiseresolve => {
setTimeout() => { resolvestring}, 5000;
};
}
异步函数doIt{ const myPromise = await slowResolvedPromiseFunc“foo”; 的console.logmyPromise; //“foo” }
async function doIt () {
const myPromise = await slowResolvedPromiseFunc ('foo');
console.log(myPromise); // 'foo'
}
doIt方法();
doIt();
```
There are a few things to note:
有几点需要注意:
* The function that encompasses the `await` declaration must include the `async` operator. This will tell the JS interpreter that it must wait until the Promise is resolved or rejected.
* The `await` operator must be inline, during the const declaration.
* This works for `reject` as well as `resolve`.
* 包含`await`关键字的函数在定义时必须有`async`关键字修饰. 它会阻塞javascript进程直到Promise执行了resolve或者reject
* `await`关键字必须和声明的变量在同一行。
*`reject``resolve`效果相同。
---
## Nested Promises vs. `Async` / `Await`
## 嵌套 Promises vs. `Async` / `Await`
Implementing a single Promise is pretty straightforward. In contrast, Chained Promises or the creation of a dependency pattern may produce "spaghetti code".
实现一个Promise很简单。 然而链式的Promise或有依赖的模式会导致“意大利面条”式的代码。
The following examples assume that the <a href='https://github.com/request/request-promise' target='_blank' rel='nofollow'>`request-promise`</a> library is available as `rp`.