如何解决地图链中的承诺功能？

Question

我希望下面代码中的所有 slowAdd() 并行发生，但我不想在它们全部解决之前执行下一个 .map() 步骤。怎么做？

async function slowAdd(a) {
  return new Promise( (resolve,reject) => setTimeout(() => resolve(a+5), 1000) )
}

async function calcArray(list) {
  return list
    .map( a => a+1 )
    .map( a => slowAdd(a) )
    .map( a => a+1 )
}

async function main() {
  const list = [1, 2, 3, 4, 5]
  const newList = await calcArray(list)
  console.log(newList)
}

main()
  .catch(err => {
    console.error(err);
  })
  .then(() => process.exit());

Answer 1

将其放入 Promise.all，然后您需要在 .then 中放置另一个 .map 以进行后续操作：

async function slowAdd(a) {
  return new Promise( (resolve,reject) => setTimeout(() => resolve(a+5), 1000) )
}

async function calcArray(list) {
  return Promise.all(
    list
      .map( a => a+1 )
      .map( a => slowAdd(a) )
  )
    .then(addedResults => addedResults.map( a => a+1 ));
}

async function main() {
  const list = [1, 2, 3, 4, 5]
  const newList = await calcArray(list)
  console.log(newList)
}

main()

如何解决地图链中的承诺功能？

How to resolve promise making function in map chain?

javascript

promise

chaining