Knockout.js observable notify 'always' and subscribe -

i have following code:

html:

<p>age:     <input data-bind="value:age" /> </p> <p>age has been changed: <span data-bind="text:agechangecount"></span> times</p> 

js:

function viewmodel() {      var self = this;      self.age = ko.observable(10).extend({         notify: 'always'     }),       self.agechangecount = ko.observable(0),      self.age.subscribe(function (val) {         console.log('someone has changed age');         self.agechangecount(self.agechangecount() + 1);     });  };  ko.applybindings(new viewmodel()); 

jsfiddle: http://jsfiddle.net/estsiim/9majtx0h/

i wondering why agechangecount wont increment when old age , new age same (when input looses focus)?

because value binding-handler ignoring model updating when new value matches old value. hence, subscriptions wouldn't run well.

see source