databinding.js

<input id="inputText" type="text" />

function DataBind(domElement, object) {
  this.element = domElement.element;
  this.attribute = domElement.attribute;
  this.event = domElement.event;

  this.value = this.element[this.attribute];
  var self = this;

  this.bindEvents = function() {
    var that = self;
    this.element.addEventListener(this.event, function(e) {
      that.value = e.target[that.attribute];
    });

    Object.defineProperty(object, object.prop, {
      get: function() {
        return that.value;
      },
      set: function(value) {
        that.element[that.attribute] = value;
        that.value = value;
      }
    })
  }
}

var domElement = {
  element: document.getElementById('inputText'),
  attribute: 'value',
  event: 'keyup'
};

var object = {
  prop: 'age'
}

var obj = new DataBind(domElement, object);
obj.bindEvents();

object.age = 23;