Simple way to debug viewmodel data bind with knockout

Debug-Knockout-JS.html

1.
<pre data-bind="text: ko.toJSON($data, null, 2)"></pre>


2.
<ul data-bind="debug: $data">

<a href="https://www.safaribooksonline.com/blog/2014/02/26/debugging-bindings-knockout-3-0/">1<a/>
<a href="https://github.com/JonKragh/knockthrough">2<a/>
  
3. <div data-bind="text: echo(value)"></div>

Debug-Knockout-JS.js

//2.
ko.bindingHandlers.debug = 
{
    init: function(element, valueAccessor) 
    {
        console.log( 'Knockoutbinding:' );
        console.log( element );
        console.log( ko.toJS(valueAccessor()) );
    }
};

//3
function echo(whatever) { debugger; return whatever; }
//Or
function echo2(whatever) { console.log(whatever); return whatever; }