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@babel/plugin-proposal-async-do-expressions

async do { .. } 表达式在异步上下文中执行一个块（其中包含一条或多条语句），块内的最终语句完成值成为异步代码的完成值。

¥The async do { .. } expression executes a block (with one or many statements in it) in an asynchronous context, and the final statement completion value inside the block becomes the completion value of the asynchronous code.

示例​

¥Example

并行发送 HTTP 请求

¥Issuing HTTP request in parallel

JavaScript
Promise.all([
  async do {
    const result = await fetch('https://example.com/A');
    await result.json()
  },
  async do {
    const result = await fetch('https://example.org/B');
    await result.json()
  },
]).then(([a, b]) => {
  console.log("example.com/A", a);
  console.log("example.org/B", b);
})

将转变为

¥will be transformed to

JavaScript
Promise.all([
  (async () {
    const result = await fetch('https://example.com/A');
    return await result.json()
  })(),
  (async () {
    const result = await fetch('https://example.org/B');
    return await result.json()
  })(),
]).then(([a, b]) => {
  console.log("example.com/A", a);
  console.log("example.org/B", b);
})

安装​

¥Installation

npm install --save-dev @babel/plugin-proposal-async-do-expressions

用法​

¥Usage

¥With a configuration file (Recommended)

babel.config.json
{
  "plugins": ["@babel/plugin-proposal-async-do-expressions"]
}

注意：该插件将 async do {} 转换为 ES2017 异步箭头函数 async () => {}。如果你针对较旧的引擎，即 Node.js 6 或 IE 11，请同时添加 @babel/plugin-transform-async-to-generator：

¥Note: This plugin transpiles async do {} to ES2017 Async arrow function async () => {}. If you target to an older engine, i.e. Node.js 6 or IE 11, please also add @babel/plugin-transform-async-to-generator:

babel.config.json
{
  "plugins": [
    "@babel/plugin-proposal-async-do-expressions",
    "@babel/plugin-transform-async-to-generator"
  ]
}

通过 CLI​

¥Via CLI

Shell
babel --plugins @babel/plugin-proposal-async-do-expressions script.js

通过 Node API​

¥Via Node API

JavaScript
require("@babel/core").transformSync("code", {
  plugins: ["@babel/plugin-proposal-async-do-expressions"],
});

参考​

¥References