JSFiddle - React, Tailwind, and code Playground

HTML

<h2>orderTime:</h2> <span data-bind="text: orderTime"></span><br />

<h2>timespan:</h2> <span data-bind="text: timespan"></span>

JavaScript

function myViewModel() {
    var self = this,i=0;
    self.orderTime = ko.observable(new Date(2013,1,1,12,0,0));
    self.timer = ko.observable(new Date());
    self.timespan = ko.computed(function() {
        return self.orderTime() + " " + self.timer();
    });    
    self.myInterval = window.setInterval(function() { 
    if(i==15){
    	clearInterval(self.myInterval);
    }
    i++; self.timer(new Date()); }, 1000);
}

ko.applyBindings(new myViewModel());