Sometimes, we want to chain promises with promises inside then() with JavaScript.

In this article, we’ll look at how to chain promises with promises inside then() with JavaScript.

How to chain promises with promises inside then() with JavaScript?

To chain promises with promises inside then() with JavaScript, we can return a promise in the then callback.

For instance, we write:

Promise
  .resolve(1)
  .then((res) => {
    console.log(res)
    return Promise.resolve(2)
  })
  .then((res) => {
    console.log(res)
    return Promise.resolve(3)
  })
  .then((res) => {
    console.log(res)
  })
  .catch((e) => {
    console.error(e);
  });

to call then with callbacks that returns another promise.

Promise.resolve returns a promise.

res has the resolved value of the previous promise.

Each then callback will run in the same order they’re listed.

Therefore, we see

1
2
3

logged.

Conclusion

To chain promises with promises inside then() with JavaScript, we can return a promise in the then callback.