JsOnDemand
==========

### Reqirements ###
Rails 1.2+

### Overview ###
This plugin helps quickly create Javascript web services (like Google 
AJAX Search API).  It mixes in a few methods to (hopefully) make your 
life easier.

### Additions to ActionView::Base ###
required_js_on_demand - This is a little Javascript to help create 
dynamic script tags.  It exposes the JavaScript object JsOnDemand.  
JsOnDemand currently has one Class called Get, here is an example of
it's usage:
new JsOnDemand.Get(relative_url, callback_function);

js_on_demand_get - This class takes one hash.  There are two keys
that are especially important for creating the JsOnDemand calls:
    :js_parameters - is a hash that consists of:
        key - query string parameter name
        value - javascript variable or literal that contains the
            value that corresponds to the query string key
    :callback - is a string that contains the function to be called
        upon completion.  Defaults to "callback"
All other keys are passed to AcionView::Base.url_for, to construct the
call to the server.

Example:
If you view looked like this.
var GetSomething = function(param1, callback) {
    <%= js_on_demand_get(:controller => "js", :action => "get_something", 
        :js_parameters => {:server_param => "param1"}) %>
};

Would be sent down to the user like:
var GetSomething = function(param1, callback) {
    new JsOnDemand.Get('/js/get_something' + '?' + 'server_param=' + 
        param1, callback);
};

Then you end users would just call your new function like this:
new GetSomething(1, function(json_data) {
    //function impl.
});


### Additions to ActionController::Base ###
render_js_on_demand(object) - It works in conjunction with required_js_on_demand, 
and makes sure that the correct callback gets called.  The object you pass in will 
have the to_json method called on it.

js_on_demand_callback - Alternatively, as of rails 1.2 there is an
options to call:
render :json => {"key","value"}.to_json, 
	:callback => js_on_demand_callback

which is equivalent to:
render_js_on_demand({"key","value"})


### Aditions to ActionController::AbstractRequest ###
js_on_demand? - This returns a boolean indicating whether or not the 
request was made from the JsOnDemand Object.  Example:
if request.js_on_demand?
	render_js_on_demand(some_object)
else
	render :text => some_object.to_json
end

The subtle difference is that if you use the render_js_on_demand the 
callback will be called, and if you don't it won't.