更清洁的承诺.所有语法？

Question

我对Node.JS相当陌生，我真的很讨厌Promise.all返回数组的语法。例如。const requiredData = await Promise.all([        getFirst(city),        getSecond(hubIds),        getThird(city, customerCategoryKey),        getFourth(request)    ])const firstData = requiredData[0];const secondData = requiredData[1];const thirdData = requiredData[2];const fourthData = requiredData[3];我需要在单独的代码行中单独获取它们。难道没有像这样const {firstData,secondData,thirdData,fourthData} = await Promise.all([        getFirst(city),        getSecond(hubIds),        getThird(city, customerCategoryKey),        getFourth(request)    ])基本上，我真的很希望有比第一个代码片段更干净的方式。

Answer 1

如注释中所述，您可以使用数组析构函数而不是使用对象析构函数：

(async () => {

  const promise1 = Promise.resolve(3);

  const promise2 = 42;

  const promise3 = new Promise((resolve, reject) => {

    setTimeout(resolve, 100, "foo");

  });

  // get all elements as variables

  const [p1, p2, p3] = await Promise.all([promise1, promise2, promise3]);

  console.log(p1, p2, p3);

})();

Answer 2

如果不是很明显，如果您可以按串行顺序运行承诺，则可以内联它们 -await

const main = async () =>

{ const a = await mock("one")

  const b = await mock("two")

  const c = await mock("three")

  const d = await mock("four")

  console.log(a, b, c, d)

}

// test funcs

const rand = n =>

  Math.floor(Math.random() * n)

const mock = (x) =>

  new Promise(r => setTimeout(r, rand(1000), x))

// run

console.log("loading...")

main().catch(console.error)

// loading...

// one two three four

如果您想并行运行承诺，但按名称检索赋值，我们可以为我们进行连接 -fromDescriptor

const fromDescriptor = (desc = {}) =>

  Promise.all( 

    Object

      .entries(desc)

      .map(([ k, px ]) => px.then(x => [ k, x ]))

  )

  .then(Object.fromEntries)

const main = async () =>

{ const init =            

    { a: mock("one")

    , b: mock("two")

    , c: mock("three")

    , d: mock("four")

    }

  

  const { a, b, c, d } =

    await fromDescriptor(init)

  console.log(a, b, c, d)

}

// test funcs

const rand = n =>

  Math.floor(Math.random() * n)

const mock = (x) =>

  new Promise(r => setTimeout(r, rand(1000), x))

// run

console.log("loading...")

main().catch(console.error)

// loading...

// one two three four