Writing nested promise javascript es6

Question

does anyone have any guides or tips on how to write a nested promises?

I am trying to turn the following nested

for loop

into a promise:

let arr = [1, 2, 3, 4, 5]





for (i = 0; i < arr.length ; i++) {



  for (j = i + 1; j < arr.length ; j++) {



      // call another asynchronous function



  }



}

I thought about doing

Promise.all

, but the iterator in the inside

for

loop starts at

j = i + 1

so I wasn't sure how to handle this with

Promise.all

.

Thanks in advance!

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Answer 1

Push them into an array

let arr = [1, 2, 3, 4, 5]
const promises = []
for (let i = 0; i < arr.length; i++) {
  for (let j = i + 1; j < arr.length; j++) {
    promises.push(new Promise((resolve, reject) => {
      setTimeout(resolve, 100, [i,j]);
    }));
  }
}
Promise.all(promises).then(values => {
  console.log(values);
});

Writing nested promise javascript es6

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