Hi Justin,

If you're thinking MVC, off-the-cuff I'd say think of the client-side
script as the Controller, the HTML as the View(s), and the server-side
stuff as the Model.  So an Ajax request is a message from the
Controller to the Model.  The data coming back knows nothing about the
Views; the Controller (the JavaScript on the page) is responsible for
taking the data and updating the Views, which are the various HTML
elements involved in the UI.  So in an MVC app, it's probably not
appropriate for the JSON to specify the HTML element that gets updated
with it; instead, it's up to the JavaScript code on the page to handle
that association.  (Although that depends; if the ID on the element is
data-derived, it could easily come from the model.)

But that's just one interpretation.  The server-side stuff could be
doing more of the heavy-lifting, so what you're seeing from the client
end of things is mostly View implementation with a  bit of Controller
thrown in, with the rest on the server out of your immediate sight.  A
lot of MVC involves blurring of the boundaries.

When you say "Most of the code samples [you've] seen...", remember
that most of the code you've seen is either sample code, or code
written "pragmatically" (whatever that's supposed to mean this week),
or code written by juniors who wouldn't know MVCs from ABCs (e.g.,
alphabetti spaeghetti, or "Spaghettios" for our American friends).

Or, of course, people could be using a different model entirely, MVC
not being the only game in town (although it's a pretty good one).

Rambling my way to my point, it's up to you.  It's up to how you
structure the data exchange between the client and server, how you set
up your pages, and how you write your script.  If you want to do
strict separation of concerns , there's no reason you can't, and in
fact the nature of the beast makes it a bit easier to think that

(The Template class can certainly help with your View implementation.)

T.J. Crowder
tj / crowder software / com

On Sep 11, 8:25 pm, Justin <[EMAIL PROTECTED]> wrote:
> Hi folks,
> I'm not an expert on front-end development and if this is the wrong
> group to post, please point me in the correct direction.
> I'm looking at ways to separate the HTML layout of a page in
> javascript from JSON data that I receive from the server. What are the
> ways to render the JSON on the client?
> Most of the code samples I've seen involve displaying the received
> JSON seem to have an intimate knowledge of how the html is laid out
> and which elements and types used to display the data. Typically what
> I see is something similar to:
> function makeHttpRequest()
> {
>         httpRequest.open("GET", url, true)
>         httpRequest.onreadystatechange = updatePage;
>         httpRequest.send();
> }
> function updatePage() {
>    if (xmlHttp.readyState == 4) {
>                 eval("var response = ("+request.responseText+")");
>                 for(var i in response.data.row.items)
>                 {
>                     document.getElementById("body").innerHTML += "<div
> id='icon'><img src='"+response.data.row.items[i].icon +"'/></div>";
>                     for(var j in response.data.row.items[i].item)
>                     {
>                         document.getElementById("body").innerHTML += "<div 
> id='item'
> onclick=\""+ response.data.row.items[i].action +"\">"+
> response.data.row.items[i].item[j] +"</div>";
>                     }
>                 }
>         }
> }
> Assuming that our view consists simple HTML with separate javascript &
> CSS files, this approach seems to intrinsically cause coupling of the
> markup with javascript. Following this approach, every section of a
> page that needs to fetch data from the server would have a different
> 'updatePage' to handle the response. In addition, if the layout of the
> page changed from a 'div' to some other type of tag, you have to
> remember to go and modify the javascript.
> I've read about the 'Template' object under prototype  and I suppose
> one thing you could do is have the server send back template string
> and with the id of the element to update along with rest of the JSON
> data and then use it after deserializing the data.
> Is there a better way to achieve this separation using prototype/
> scriptaculous?
> Thanks,
> Justin
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