Is there a reason I would use Knockout MVC instead of Knockout JS?

Solution 1:

Knockout MVC is the bastard child of WebForms. It routes all viewmodel methods through controller actions, meaning everything that happens has to bounce to the server and back. I cannot understand why anyone would take a framework like knockout, which is intended to be CLIENT SIDE MVVM, and force it to call the server for every function.

In addition, performing those methods on the server means the entire viewmodel needs to be passed to the server, and back to the client, for every function call. This is incredibly wasteful.

Using Knockout MVC means sacrificing all the performance benefits of client-side code for the benefit of not having to write javascript. The same trade-off WebForms made. It is not a good one. It is an antipattern.

If Knockout MVC dies tomorrow, the web will be a better place.

Solution 2:

I just ran across this question which has some pretty negative responses. I'm going to quickly add my two cents worth.

I have only just started using KnockoutJS. Since I'm building ASP.NET MVC apps, it seemed logical to me to use something like Knockout MVC. For the most part, it seems like a great idea. I don't want to be spending time writing javascript and  comments through my pages if I can do the same using .Net functionality that I know and love.

Having said that... yes, there are limitations to KMVC at the moment. Sending the entire model back to the server is a big one. So what I've done is started my own fork of knockout-mvc. The changes have been necessarily rushed at the moment. But I now have ability to:

create sub-contexts (with completely different models or components of the view model)
pass selected portions of model back when calling the server
expect a different model back from a call than what was sent
fire events around the ajax calls
support more html5 input types
pass anti forgery tokens to the server via headers (for ajax calls)
probably more I've forgotten

I'm hoping to get back soon and really clean up what I've done. Hopefully, the author will include these changes in his code. If not, I guess I'll keep my own fork going. Either way, there's light at the end of the tunnel. KMVC might need work as it stands, but I believe the concept was definitely worth doing.

I definitely think

If Knockout MVC dies tomorrow, the web will be a better place.

was a bit harsh.

Edit:

I was looking at the comments and looked again at what the original question was. Having done that I think a little bit more should be added to my answer:

First, the original question was Is there a reason I would use Knockout MVC instead of Knockout JS? To answer/clarify (maybe I'm just being picky) that: Knockout MVC is a framework designed to make it easier to integrate KnockoutJS with your ASP.NET MVC app. It does this mostly by using familiar, strongly-typed constructs to generate KnockoutJS tags. It is not a replacement for KnockoutJS. By all means use KnockoutJS. The question is really whether to use Knockout MVC as well.

Having said that, the choice is still yours as a developer to choose when to use various aspects of all the tools available to you. If you want to handle a certain aspect of functionality by performing a full request back to the server, then do that. If you want to perform an ajax request to retrieve/update data, then do that. If you want to perform functionality purely client-side, then do that.

Using Knockout MVC does not prevent you from utilising KnockoutJS to it's fullest. Using Knockout MVC does not prevent you from writing additional javascript to handle as much client-side functionality as you want. Just because Knockout MVC provides you with a short-cut to generate ajax callbacks to the server does not mean you have to use them. Although, if you application ever persists data, it's going to have to call home at some point.

There are reasons for building an application backend using ASP.NET MVC compared to just using Apache to serve static HTML and script files. Knockout MVC allows you to continue to take advantage of those same benefits to assist with KnockoutJS integration.

Solution 3:

I find Tyrsius' answer a bit too negative. Knockout MVC is still in early development, but from what I can see it has some advantages and is less server heavy than Webforms for example. Visiblity dependancies get handles entirely on the client, only when using functions a call is done to the server. When working with complex data structures, it sometimes is required to go via the server anyways, so then Knockout MVC might be a good way to save on writing a lot of Ajax-handling yourself.

It is true it always sends the entire model back and forth, which gives some overhead as opposed to building it yourself. But I wouldn't write it off entirely. Especially when it gets proper client-side handling for complex validations in the future.

Solution 4:

I've come across this post after searching a bit about knockout mvc. Although I agree with the waste of network bandwidth, I'm quite seduced by that line of code :

@{
  var ko = Html.CreateKnockoutContext();
 }

This is a neat and clean way for generating the knockout viewmodel. Has anyone used knockout MVC just for that feature and without moving all the logic to the server side ?

Solution 5:

The beauty of Knockout.js is that you can get your application served by simply passing JSON back and forth from the server without having to push an entire view that the server had to chunk away at to generate HTML.

It seems very counter-intuitive to put that back on the server again! If that interests you, you're better off using the razor syntax to accomplish your binding in the first place.

My suggestion would be to use knockout.js to do your binding so that the binding takes place on the client rather than the server if this is the goal you're going for. If you want your view to be data bound on the server, use razor.