How to write asynchronous code in conditional statements?

Question

Node.js

Follow-up to this question ( How to write asynchronous code correctly? ), but without a direct link.
There is a function in which data can be repeatedly modified asynchronously, after which it is passed to callback functions. When should a callback be made?

function(data, callback){
  if(data.someCondition1){
    doAsyncCode(data, function(err, result){
      ...
    }
  }
  if(data.someCondition2){
    doAsyncCode(data, function(err, result){
      ...
    }
  }
  // В конце нужен коллбэк
}

And how to ensure that the data is modified sequentially? Split into subfunctions, such as in the example by reference?
Where can one read about such examples?

Answer 1

The easiest way is to use the async module and its waterfall method .

Answer 2

The easiest way is not to suffer and use async / await from ES7, though so far only with a preprocessor, example , your specific case .