- Objective:
- Breadcrumb:
# 概念阐释
## 语义
[[js 异步 Promise.all()并发处理]]的语法糖格式。
## 语法
### print时写`await`
```js
async function concurrent() {
const firstPromise = firstAsyncThing();
const secondPromise = secondAsyncThing();
console.log(await firstPromise, await secondPromise);
}
```
### `await Promise.all()`
```js
async function asyncPromAll() {
const resultArray = await Promise.all([asyncTask1(), asyncTask2(), asyncTask3(), asyncTask4()]);
for (let i = 0; i<resultArray.length; i++){
console.log(resultArray[i]);
}
}
asyncPromAll();
```
# 实例
```js
const serveDinner = async () => {
const vegetablePromise = steamBroccoli();
const starchPromise = cookRice();
const proteinPromise = bakeChicken();
const sidePromise = cookBeans();
console.log(`Dinner is served. We're having ${ await vegetablePromise}, ${ await starchPromise}, ${ await proteinPromise}, and ${ await sidePromise}.`)
};
serveDinner();
```
```js
async function serveDinnerAgain(){
// Promise.all的值为数组
let foodArray = await Promise.all([steamBroccoli(), cookRice(), bakeChicken(), cookBeans()]);
console.log(`We're having ${foodArray[0]},${foodArray[1]},${foodArray[2]},${foodArray[3]}.`);
};
serveDinnerAgain();
```
# 相关内容
注意：如果我们有多个真正独立的承诺，我们想要完全并行执行，我们必须使用单独的.then()函数，并避免使用await停止我们的执行。
# 问题
# 问题答案
# 参考资料
- [handling independent promiises](https://www.codecademy.com/journeys/full-stack-engineer/paths/fscj-22-front-end-development/tracks/fscj-22-async-javascript-and-http-requests/modules/wdcp-22-learn-javascript-syntax-async-await-40c16baa-3867-4d62-917d-5b66da1a85f5/lessons/async-await/exercises/concurrency)
- [await promise.all](https://www.codecademy.com/journeys/full-stack-engineer/paths/fscj-22-front-end-development/tracks/fscj-22-async-javascript-and-http-requests/modules/wdcp-22-learn-javascript-syntax-async-await-40c16baa-3867-4d62-917d-5b66da1a85f5/lessons/async-await/exercises/await-promise-all)