A simple Model

spineModel.js

/* 
var model = new BackboneModel({
  key : value
})
model.add("key", "value")
model.listen("key", function(){

})
*/

/**
 * Spine Model
 *
 * This is a simple SpineModel which can be used to set key-value pairs
 * and add listeners to have complex functionalities in the future.
 * 
 * add - (key, value) adds key and value to the model instance
 * set - (obj) adds the obj's keys and values to the existing model instance
 * on - (eventName, cb) adds events
 * emit - (eventName) triggers an event
 * onchange - (key) listens to changes on a particular key in the model instance
 *
 * Author - Kaushik Thirthappa (thirthappa.kaushik@gmail.com)
 */

function SpineModel () {

  var events = {};

  // custom setter
  this.add = function (key, value) {
	  this[key] = value;
  }

  // custom setter
  this.set = function (obj) {
    for(var key in obj) {
      this[key] = obj[key];
    }
  }

  // on event
  this.on = function (eventName, cb) {
    if (!events.hasOwnProperty(eventName)) {
      events[eventName] = cb;
    }
  }

  // emit those events
  this.emit = function (eventName) {
    if (events.hasOwnProperty(eventName)) {
      console.log('the event %s is being triggered !!', eventName);
      events[eventName]();
    } else {
      return;
    }
  }

  // adding listeners
  this.onchange = function (key) {
    console.log('setting onchange to %s', key);
    Object.defineProperty(this, key, {
      get: function() {
        return key;
      },
      set: function(value) {
        console.log('setting the variable');
        key = value;
      }
    });
  }

}

// Execute
var model = new SpineModel();

/**
 * Apologies on the loggers
 */
console.log('******************** Adding a as a new key with 10 as value using add function ********************');
model.add('a', 10);
console.log(model.a);
console.log('******************** Loggin model right after ********************');

console.log('******************** Adding name as a new key with Dron as value using set function ********************');
model.set({name: 'Dron'});
console.log(model.name);
console.log('******************** Loggin model right after ********************');

console.log('******************** Adding an event now ********************');
model.on('logger', function() {
  console.log('finished executing the event.......');
});

model.emit('logger');
console.log('******************** Triggering an event now ********************');

model.onchange('name'); // add listener
model.name = 'Kaushik';
console.log(' ----- changing the name after adding listener using native assignment operator -----');
console.log(model.name); 
console.log('******************** Logging the model name ********************')

console.log(' ----- changing the name after adding listener using set for spineModel ------');
model.set({name: 'shruti'});
console.log(model.name);
console.log('******************** Logging the model name ********************')