javascript - knockout computed object not working when working with JSON -

I'm new to knockout, the problem is that I try to load the object from Jason and computed Please use the value also please see that jsfiddle example and let me know what I am doing, it should display "Hello World" + "Start Date" (in the third line)

  self Starttextt = ko.computed (function () {return "Hello world" + this.start ();}, this); It is noteworthy that this calculation remains in the object "events" object (which is full of JSN) while "event" objects live in the ViewModel object.  
 Appreciate your help, thank you   
 
 
 There are problems:  
 You need to fix your  event  function to take some parameters to fill with the data: 
 
  function event (data) ) {Var self = this; Self.title = ko.observable (data.title); Self.start = ko.observable (data.start); Self.starttextt = ko.computed (function () {return "hello world" + this.start ();}, this); }  
 
 then writing  var data = [event]; Create an array with the  event  function and it does not in any way mapping you  objs  on the array  map  Need to call: 
 
  var objs = JSON.parse (js); Var data = objs.map (function (e) {new event (e)});  
 
 and you should use  data  instead of  obj  
 
  var viewModel = in your code Requires = function () {var itself = this; Self.events = ko.observableArray (data); };  
 
 Demo 
 
 However, you do not need to write these mapping code because there is already a plugin that is designed to control such situations. 
 
 Your sample has been re-written with the mapping plugin: 
 
  var mapping = {create: function (options) {var event = ko.mapping.fromJS ( Options.data); Event.starttextt = ko.computed (function () {returns "hello world" + event.start ();}, event); Event of return; }} Var viewModel = function () {var self = this; Self.events = ko.mapping.fromJSON (JS, Mapping); };  
 
 Demo