create or push

createorpush.js

var util = require('util');
global.$ = global.jQuery = require('jquery');
$.extend = require('extend');
var _ = require('underscore');
var Backbone = require('backbone');
Backbone.$ = $;
require('backbone-nested');

var Model = Backbone.NestedModel.extend({
  createOrPush: function(key, newValue) {
    var value = this.get(key);
    if (value && value.length > 0) {
      value.push(newValue);
    } else {
      value = [newValue];
    }
    var setObj = {};
    setObj[key] = value;
    this.set(setObj);
  }
});

var source = new Model();


source.createOrPush('a.b.c', 'ad');
source.createOrPush('a.b.c', 'adXXX');

console.log(util.inspect(source.toJSON(), {showHidden: false, depth: null}));