Return A Message From ViewModel

Create one controller in our MVC application. Add bellow action method and view for the same.

public ActionResult Index()
       {
           return View();
       }

Now download the latest knockout Js file from here http://knockoutjs.com

Add JavaScripts. I have created Before-KO.js file to add our knockout Js code.

<script src="~/Scripts/jquery-2.2.0.js"></script>
<script src="~/Scripts/knockout-3.4.0.js"></script>
<script src="~/Scripts/Before-KO.js"></script>

Now add below code to our Before-KO.js file.

$(document).ready(function () {
    //debugger;
    var p = 500;
    var viewModel = {
    };
    viewModel.priceRating = ko.computed(function () {
        if(p != null)
        {
            if (p > 5000) {
                return "you can not buy product because it is expensive";
            }
            else {
                return "you can buy products upto 5000";
            }
        }
    },
        viewModel);
    ko.applyBindings(viewModel);
})

Now if we run the application we will get message as

you can buy products upto 5000