据我所知，在ES7/ES2016中，在代码中放置多个await将类似于用promise链接.then（），这意味着它们将一个接一个地执行，而不是并行执行。例如，我们有以下代码：
await someCall();
await anotherCall();
我是否正确理解只有当someCall（）完成时才会调用另一个otherCall（）？并行调用它们最优雅的方式是什么？
我想在Node中使用它，所以也许有一个异步库的解决方案？
编辑：我对这个问题中提供的解决方案不满意：由于异步生成器中的非并行等待承诺，所以速度变慢，因为它使用生成器，我问的是一个更通用的用例。
当前回答
我创建了一个助手函数waitAll，也许它可以让它更甜。它目前只在nodejs中工作，在浏览器chrome中不工作。
//const parallel = async (...items) => {
const waitAll = async (...items) => {
//this function does start execution the functions
//the execution has been started before running this code here
//instead it collects of the result of execution of the functions
const temp = [];
for (const item of items) {
//this is not
//temp.push(await item())
//it does wait for the result in series (not in parallel), but
//it doesn't affect the parallel execution of those functions
//because they haven started earlier
temp.push(await item);
}
return temp;
};
//the async functions are executed in parallel before passed
//in the waitAll function
//const finalResult = await waitAll(someResult(), anotherResult());
//const finalResult = await parallel(someResult(), anotherResult());
//or
const [result1, result2] = await waitAll(someResult(), anotherResult());
//const [result1, result2] = await parallel(someResult(), anotherResult());
其他回答
这可以通过Promise.allSettled（）实现，它类似于Promise.all（），但没有快速失败行为。
async function Promise1() {
throw "Failure!";
}
async function Promise2() {
return "Success!";
}
const [Promise1Result, Promise2Result] = await Promise.allSettled([Promise1(), Promise2()]);
console.log(Promise1Result); // {status: "rejected", reason: "Failure!"}
console.log(Promise2Result); // {status: "fulfilled", value: "Success!"}
注意：这是一个边缘功能，浏览器支持有限，因此我强烈建议为该功能添加polyfill。
更新：
最初的答案使正确处理拒绝承诺变得困难（在某些情况下是不可能的）。正确的解决方案是使用Promise.all：
const [someResult, anotherResult] = await Promise.all([someCall(), anotherCall()]);
原答覆：
只需确保在等待其中一个函数之前调用这两个函数：
// Call both functions
const somePromise = someCall();
const anotherPromise = anotherCall();
// Await both promises
const someResult = await somePromise;
const anotherResult = await anotherPromise;
await Promise.all（[someCall（），anotherCall（）]）；正如已经提到的那样，它将充当线程围栏（在CUDA这样的并行代码中非常常见），因此它将允许其中的所有承诺在不相互阻止的情况下运行，但将阻止执行继续，直到解决所有问题。
另一种值得分享的方法是Node.js异步，如果任务直接与API调用、I/O操作等有限资源的使用相关联，它还允许您轻松控制通常需要的并发量。
// create a queue object with concurrency 2
var q = async.queue(function(task, callback) {
console.log('Hello ' + task.name);
callback();
}, 2);
// assign a callback
q.drain = function() {
console.log('All items have been processed');
};
// add some items to the queue
q.push({name: 'foo'}, function(err) {
console.log('Finished processing foo');
});
q.push({name: 'bar'}, function (err) {
console.log('Finished processing bar');
});
// add some items to the queue (batch-wise)
q.push([{name: 'baz'},{name: 'bay'},{name: 'bax'}], function(err) {
console.log('Finished processing item');
});
// add some items to the front of the queue
q.unshift({name: 'bar'}, function (err) {
console.log('Finished processing bar');
});
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在我的例子中，我有几个任务要并行执行，但我需要对这些任务的结果做一些不同的事情。
function wait(ms, data) {
console.log('Starting task:', data, ms);
return new Promise(resolve => setTimeout(resolve, ms, data));
}
var tasks = [
async () => {
var result = await wait(1000, 'moose');
// do something with result
console.log(result);
},
async () => {
var result = await wait(500, 'taco');
// do something with result
console.log(result);
},
async () => {
var result = await wait(5000, 'burp');
// do something with result
console.log(result);
}
]
await Promise.all(tasks.map(p => p()));
console.log('done');
输出：
Starting task: moose 1000
Starting task: taco 500
Starting task: burp 5000
taco
moose
burp
done
（异步函数（）{功能等待（毫秒，数据）{console.log（'启动任务：'，数据，毫秒）；return new Promise（resol=>setTimeout（resolve，ms，data））；}var任务=[异步（）=>{var result=等待等待（1000，'moose'）；//做些有结果的事console.log（结果）；},异步（）=>{var result=等待等待（500，'taco'）；//做些有结果的事console.log（结果）；},异步（）=>{var result=等待等待（5000，'burp'）；//做些有结果的事console.log（结果）；}]await Promise.all（tasks.map（p=>p（）））；console.log（“one”）；})();
我创建了一个助手函数waitAll，也许它可以让它更甜。它目前只在nodejs中工作，在浏览器chrome中不工作。
//const parallel = async (...items) => {
const waitAll = async (...items) => {
//this function does start execution the functions
//the execution has been started before running this code here
//instead it collects of the result of execution of the functions
const temp = [];
for (const item of items) {
//this is not
//temp.push(await item())
//it does wait for the result in series (not in parallel), but
//it doesn't affect the parallel execution of those functions
//because they haven started earlier
temp.push(await item);
}
return temp;
};
//the async functions are executed in parallel before passed
//in the waitAll function
//const finalResult = await waitAll(someResult(), anotherResult());
//const finalResult = await parallel(someResult(), anotherResult());
//or
const [result1, result2] = await waitAll(someResult(), anotherResult());
//const [result1, result2] = await parallel(someResult(), anotherResult());
