knockout.js - How to call a nested function from out side knockout js -

i learning knockout js. still understanding not clear. apologized ask kind of question.

see code first see trying achieve. here jsfiddle link http://jsfiddle.net/tridip/vvdvgnfh/

<button data-bind="click: $root.printproduct()">print product</button> <table id="table1" cellspacing="0" cellpadding="0" border="0">     <tr>         <th style="width:150px">product</th>         <th>price ($)</th>         <th>quantity</th>         <th>amount ($)</th>     </tr>      <tbody data-bind='template: {name: "ordertemplate", foreach: lines}'></tbody> </table>  <script type="text/html" id="ordertemplate">     <tr>         <td><select data-bind='options: products,                                optionstext: "name",                                optionscaption:"--select--",                                value: product'>                                </select>         </td>          <td>             <span data-bind='text:price' ></span>         </td>         <td>             <input data-bind='value:quantity' />         </td>          <td ><span data-bind='text:subtotal()'></span></td>      </tr> </script>      var cartline = function () {           var self = this;           self.products = ko.observablearray(_products);           self.product = ko.observable(1);           self.price = ko.observable(1);           self.quantity = ko.observable(1);             self.product.subscribe(function(item){               if(!item)               {                  self.price(0);                  self.quantity(0);                  return;               }              self.price(item.price);              self.quantity(item.quantity);           });            self.subtotal = ko.computed(function () {                return self.price() * self.quantity();           },self);          self.printproduct = function() {              alert('hello');         }                   };        var cart = function () {           // stores array of lines, , these, can work out grandtotal           var self = this;           self.lines = ko.observablearray([new cartline()]); // put 1 line in default         };        ko.applybindings(new cart()); 

print product out side button if need call function defined in cartline how access ? @ possible ?

thanks

you can't call function on cartline outside loop it's outside context (scope), 1 approach can follow have click binding on row, when user clicks row, calls function on root scope save reference selected cartline:

 <tr data-bind="click: $root.selectrow">     <td><select data-bind='options: products, 

and cart function has selectrow , print functions:

  var cart = function () {       // stores array of lines, , these, can work out grandtotal       var self = this;       self.lines = ko.observablearray([new cartline()]); // put 1 line in default       self.selectrow = function(line) {           self.selected = line;       }        self.print = function() {           if(self.selected) {               self.selected.printproduct();           }       }   }; 

then print button calls print function on root delegates selected cartline

<button data-bind="click: $root.print">print product</button> 

here update jsfiddle http://jsfiddle.net/omerio/vvdvgnfh/1/