Asynchronous constructor

Question

How can I best handle a situation like the following?

I have a constructor that takes a while to complete.

var Element = function Element(name){
            


        

Answer 1

This is a bad code design.

The main problem is in the callback your instance it's not still execute the "return", this is what I mean

var MyClass = function(cb) {
  doAsync(function(err) {
    cb(err)
  }

  return {
    method1: function() { },
    method2: function() { }
  }
}

var _my = new MyClass(function(err) {
  console.log('instance', _my) // < _my is still undefined
  // _my.method1() can't run any methods from _my instance
})
_my.method1() // < it run the function, but it's not yet inited

So, the good code design is to explicitly call the "init" method (or in your case "load_nucleus") after instanced the class

var MyClass = function() {
  return {
    init: function(cb) {
      doAsync(function(err) {
        cb(err)
      }
    },
    method1: function() { },
    method2: function() { }
  }
}

var _my = new MyClass()
_my.init(function(err) { 
   if(err) {
     console.error('init error', err)
     return
   } 
   console.log('inited')
  // _my.method1()
})