JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://knockoutjs.com/downloads/knockout-2.2.1.js"></script>
<input data-bind="text: direction, event: { blur: directionChange }" />
<button>test</button>nr value:<span data-bind="text:number"></span>

JavaScript

vm = function () {
       this.number = ko.observable(1),
       this.direction = ko.observable(''),
          this.directionChange = function(){
           if (this.direction() == 'up') {
               this.number(number +1);
           }
           else if (this.direction() == 'up') {
               this.number(number -1);
           }
       };
   }

   ko.applyBindings(new vm());