weX5如何绑定KO对象

define(function(require){
   var $ = require("jquery");
   var justep = require("$UI/system/lib/justep");
   var Model = function(){
           this.callParent();
           this.myText = justep.Bind.observable("bind!");
   };
   Model.prototype.button2Click = function(event){
           this.myText.set(false);
   };  

   return Model;
});