async / await Promise.all（），但是在promise解析时得到响应

Question

Run all promises in parallel using Promise.all() but get response of each promise as it resolves and do processing on that.

Is there a work around like I can attach a callback to promises.resolve that as a certain promise resolves it calls a callback

Example

let p1 = Promise.resolve(1)
let p2 = Promise.resolve(2)
let p3 = Promise.resolve(3)

Promise.all([p1,p2,p3])

function processData(data)
{
.... 
}

I want to run all of them in parallel but don't want to wait till all of them get resolved but instead call processData() as soon as a promise resolves for each of them.

Answer 1

Iterate over the promises with forEach instead, attaching processData to each in a .then :

 const processData = console.log; let p1 = Promise.resolve(1); let p2 = Promise.resolve(2); let p3 = Promise.resolve(3); [p1, p2, p3].forEach(prom => prom .then(processData) .catch((err) => { /* handle errors */ }) ); 

Answer 2

You can attach a .then after resolving and assign processData as a callback.

let p1 = Promise.resolve(1).then(processData);
let p2 = Promise.resolve(1).then(processData);
let p3 = Promise.resolve(1).then(processData);

Promise.all([p1,p2,p3])

Answer 3

Just don't use Promise.all() :

let p1 = Promise.resolve(1).then(processData);
let p2 = Promise.resolve(2).then(processData);
let p3 = Promise.resolve(3).then(processData);

If you need to call processData as soon as a promise resolves but want to wait for all promises to resolve before continuing then use Promise.all() only for the wait but call processData inside each promise's .then() :

(async () {
  let p1 = Promise.resolve(1).then(processData);
  let p2 = Promise.resolve(2).then(processData);
  let p3 = Promise.resolve(3).then(processData);

  await Promise.all([p1,p2,p3]);

  // continue processing..

})();