@babel/plugin-proposal-async-do-expressions
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.
Example
Issuing HTTP request in parallel
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);
})
will be transformed to
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);
})
Installation
npm install --save-dev @babel/plugin-proposal-async-do-expressions
Usage
With a configuration file (Recommended)
{
"plugins": ["@babel/plugin-proposal-async-do-expressions"]
}
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:
{
"plugins": [
"@babel/plugin-proposal-async-do-expressions",
"@babel/plugin-transform-async-to-generator"
]
}
Via CLI
babel --plugins @babel/plugin-proposal-async-do-expressions script.js
Via Node API
require("@babel/core").transformSync("code", {
plugins: ["@babel/plugin-proposal-async-do-expressions"],
});