延迟承诺，

Question

所以，我有两个承诺，我想在屏幕上打印，中间有 3 秒的延迟。我将如何实现它。下面是代码。const promiseOne = new Promise(function(resolve, reject) {  resolve("Hello")});const promiseTwo = new Promise(function(resolve, reject) {  resolve("Good Morning")});Promise.all([promiseOne, promiseTwo]).then(function() {  setTimeout(() => {    const response = Promise.all.next();    console.log(response);  }, 3000);});

Answer 1

我建议你使用延迟功能。首先你遍历数组中的每个响应并使用它们之间的延迟

const promiseOne = new Promise(function(resolve, reject) {

  resolve("Hello")

});

const promiseTwo = new Promise(function(resolve, reject) {

  resolve("Good Morning")

});

function delay(ms) {

  return new Promise(resolve => setTimeout(resolve, ms));

}

Promise.all([promiseOne, promiseTwo]).then(async function(resps) {

     

   for(let res of resps){

   console.log(res);

    await delay(3000)

   }   

});

Answer 2

const promiseOne = new Promise(function(resolve, reject) {

    resolve("Hello")

});

const promiseTwo = new Promise(function(resolve, reject) {

    resolve("Good Morning")

});

Promise.all([promiseOne, promiseTwo]).then(function(all) {

    return new Promise((resolve,reject)=>{

        setTimeout(()=>{

            resolve(all);

        }

        , 3000);

    });

}).then(console.log)

在 中返回新的 Promise then，该 Promise 等待x毫秒并解决它。

接下来做任何事情then

Answer 3

如果您只想延迟日志，则可以按照@Daniel Rodríguez Mezaresponse的说明添加参数。

但是如果你想延迟response任何一个承诺promiseOne，promiseTwo那么你应该setTimeout(() => resolve("Hello"), 300);在各自的承诺中使用，如下所示。也不要setTimeout在里面使用Promise.All。

根据OP 的评论，resolve promiseTwo 3 seconds我在解决后更新了答案promiseOne。

在这里，我将resolveof分配给了 3 秒后在内部使用的promiseTwo全局变量。resolvePromiseTwopromiseOneresolve promiseTwo

注意我已经使用.thenafterpromiseOne和promiseTwojust to verify output。你可以省略两者。

let resolvePromiseTwo = null;

const promiseOne = new Promise(function(resolve, reject) {

  resolve("Good Morning")

  setTimeout(() => resolvePromiseTwo("Hello"), 3000);

}).then(res => {

  console.log('promiseOne resolved');

  return res;

});

const promiseTwo = new Promise(function(resolve, reject) {

  resolvePromiseTwo = resolve;

}).then(res => {

  console.log('promiseTwo resolved');

  return res;

});

Promise.all([promiseOne, promiseTwo]).then(function(response) {

  console.log('Promise.all');

  console.log(response);

});

Answer 4

你已经非常接近了，你只需要从的结果中接收值，Promise.all然后处理该信息，如下所示：

const promiseOne = new Promise(function(resolve) {

    resolve("Hello")

});

const promiseTwo = new Promise(function(resolve) {

   resolve("Good Morning");

});

Promise.all([promiseOne, promiseTwo])

    .then(function(response) {

        setTimeout(() => {

            console.log(response);

        }, 3000);

    });

编辑 根据 OP 给出的说明，他需要的是以下内容：

第一个promise resolve后，等待3秒再执行第二个promise。

const promiseOne = new Promise(function(resolve) {

    resolve("Hello")

});

const promiseTwo = new Promise(function(resolve) {

   resolve("Good Morning");

});

async function resolveWithDelay(delay = 3000) {

    const res1 = await promiseOne;

    console.log(res1);

    setTimeout(async () => {

        const res2 = await promiseTwo;

        console.log(res2);

    }, delay);

}

resolveWithDelay();