async init

approach1.js

function Model(stuff) {
  this.d_stuffInterface = stuff;
}

Model.prototype.init = function (){
  return this.d_stuffInterface.getData().then(function(data){
    this.d_data = data;
    return data;
  }.bind(this);
}

//Don't provide this, force all work in init
// Model.prototype.getData = function(){
//   //need to assert continueInit was called! 
// }

approach2.js

function Model(stuff) {
  this.d_stuffInterface = stuff;
  this._initDefer = createDefer();
}

Model.prototype.init = function(){
 this.d_stuffInterface.getData().then(function(data){
    this._initDefer.resolve(data);
  }.bind(this);
}

//getData is a cached promise all access happens that way
//this should probably be a getter
Model.prototype.getData = function(){
  return this._initDefer.promise; 
}

function createDefer(){
    var deferal = {};
    deferal.promise = new Promise(function(resolve,reject){
      deferal.resolve = resolve;
      deferal.reject = reject;
    });
    return deferal;
}

gistfile1.txt

function Model(stuff) {
  this.d_stuffInterface = stuff;
}

//getting data is init
Model.prototype.getData = function(){
  if (!this.initP){
    this.initP = this.d_stuffInterface.getData();
  }
  return this.initP.then(function(data){
    return data;
  }.bind(this);  
}