How to return a value from a nested function?

Question

JavaScript

hello there is a function

class ShowReaders
  constructor:(@listreaderdiv, @currentreaderdiv )->
       console.log('mainclass')
       @currentReader
       @testedReaders

...
...



  getCurrentReader:(url)->
       $.post "/ajax/#{url}", (data)->
            console.log('data ',data['current'])
            @currentReader = data['current']



  create:->
       @getCurrentReader('getcurrentreader')
       $('#currentreader').empty()
       console.log( @currentReader)

The question is why, when assigning the value of the currentReader variable in the getCurrentReader method, the variable is nominally assigned, and when called in the create method, it already returns undefine.

Answer 1

Have you been doing asynchronous programming for a long time or just started today?
Because you need at least this (sorry, not strong in coffescript, I wrote it as best I could):

class ShowReaders
  constructor:(@listreaderdiv, @currentreaderdiv )->
       console.log('mainclass')
       @currentReader
       @testedReaders

...
...



  getCurrentReader:(url, callback)->
       $.post "/ajax/#{url}", (data)->
            console.log('data ',data['current'])
            @currentReader = data['current']
            @onGetCurrentReader()

  create:->
       @getCurrentReader('getcurrentreader')

  onGetCurrntReader:->
      $('#currentreader').empty()
      console.log( @currentReader)

The following seems to me the most logical option:

function ShowReaders() {
  this.currentReader = null;
  this.testedReaders = null;
}

ShowReaders.prototype.getCurrentReader = function(url, callback) {
  $.post(url, this.onGetCurrentReader.bind(this, callback));
};

ShowReaders.prototype.onGetCurrentReader = function(callback) {
  this.currentReader = data['current'];
  callback();
};

ShowReaders.prototype.create = function() {
  this.getCurrentReader('getcurrentreader', function() {
    $('#currentreader').empty();
    console.log(this.currentReader)
  }.bind(this));
};