[js] 第410天 js循环中调用异步的方法，如何确保执行结果的顺序是正确的？ #2446

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[js] 第410天 js循环中调用异步的方法，如何确保执行结果的顺序是正确的？#2446

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on May 29, 2020

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第410天 js循环中调用异步的方法，如何确保执行结果的顺序是正确的？

我也要出题

added

on May 29, 2020

An example:

let searchApi = function(arg){
    return new Promise((resolve,reject)=>{
        setTimeout(()=>{
            console.log(arg)
            resolve(arg)
        }, 20)
    })
};
let fields = [1,2,3,4];
let arr = new Array(fields.length);
await fields.forEach(async (vvv, index) => {
    const obj = await searchApi(vvv)
    arr[index] = obj
    const tempArr = JSON.parse(JSON.stringify(arr))
    if(tempArr.every(Boolean)){
        console.log(arr)
    }
})

Promise.all?

  function getPromise(time) {
    return new Promise(function (resolve, reject) {
      setTimeout(()=>{
        resolve(time)
      }, time)
    })
  }
  let times = [2000, 5000, 3000, 6000]
  async function fn(arr) {
    for(const times of arr) {
      const res = await getPromise(times)
      console.log('fn------', res)
    }
  }
  fn(times)

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