JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://ajax.aspnetcdn.com/ajax/globalize/0.1.1/globalize.min.js"></script>
<div data-bind="text: dates"></div>
<div data-bind="text: raw"></div>

JavaScript

ko.extenders.date = function(target, format) {
    var raw = ko.observable();
    var result = ko.computed({
        read: function() {
            var value = target();
            if(typeof value === "string") {
                value = new Date(value);                
            }
            
            raw(value);
            
            format = typeof format === "string" ? format: undefined;
            value = Globalize.format(value, format);
            
            return value;        
        },
        write: target
    });
    
    result.raw = raw;
    return result;    
}

ViewModel = function() {
    this.dates = ko.observable("2013-06-17T11:56:18.4537687Z").extend({ date: true });
    this.raw = this.dates.raw;
}

ko.applyBindings(new ViewModel());