javascript - 使用异步回调函数迭代 Map 的条目

Question

我想迭代 Map 的条目带有异步回调函数。应立即为所有元素启动回调函数。

我最终得到了以下代码，它可以工作但看起来太复杂了:

async function test() {
  const map1 = new Map();

  map1.set('a', 1);
  map1.set('b', 2);
  map1.set('c', 3);

  await Promise.all(Array.from(map1.entries()).map(async([
    key,
    value
  ]) => {
    await doSomeThing(key, value);
    await doSomeOtherThing(key, value);
  }
}

有没有更简单的方法来实现这一目标？

Answer 1

你可以做一些更短的事情

• Array.from(map1.entries()) 可以重写为 [...map1]
• 据我所知，doSomeOtherThing 不依赖于 doSomeThing，因此我们可以同时调用它们两个

await Promise.all(
  [...map1].flatMap(([key, val]) => [
    doSomeThing(key, val),
    doSomeOtherThing(key, val),
  ])
)

const doSomeThing = (key, val) =>
  new Promise(res => {
    console.log("doSomeThing start", key, val)
    setTimeout(() => {
      console.log("doSomeThing finish", key, val)
      res()
    }, 1000)
  })
const doSomeOtherThing = (key, val) =>
  new Promise(res => {
    console.log("doSomeOtherThing start", key, val)
    setTimeout(() => {
      console.log("doSomeOtherThing finish", key, val)
      res()
    }, 2000)
  })

async function test() {
  const map1 = new Map()

  map1.set("a", 1)
  map1.set("b", 2)
  map1.set("c", 3)

  /*
  await Promise.all(
    Array.from(map1.entries()).map(async ([key, value]) => {
      await doSomeThing(key, value)
      await doSomeOtherThing(key, value)
    })
  )
  */

  await Promise.all(
    [...map1].flatMap(([key, val]) => [
      doSomeThing(key, val),
      doSomeOtherThing(key, val),
    ])
  )
}

test().then(() => {
  console.log("done")
})