Where should JavaScript with embedded Ruby code go in a Rails 3.1 app?

For a Rails 3.1 app, some of my site wide JavaScript is only included when certain real time,开发者_运维百科 instance specific conditions are met. This means I can't put it in the new asset pipeline's application.js because that isn't parsed by erb for embedded Ruby within the current context. Basically, I'm including keyboard shortcuts, based on the current_user that is logged in.

My question: where should this JavaScript with embedded code go, so that the embedded Ruby is still parsed for each page access with the proper context (i.e. current, logged in user)?

The answer seems to just be to put it in the application.html.erb layout view at the bottom, but this seams like I'm hiding away javascript code in a non intuitive location.

I've tried creating an application2.js.erb file, but then I got errors about undefined variables, which I think might be because the asset engine only parses this file once before the output is cached and the scope isn't correct yet for things like current_user.

So, using application.html.erb works just fine here, and this isn't so much a question of how to get it to work functionally. Instead, I'm wondering if there's a more elegant way to incorporate the asset pipeline model here with my requirements and still keep most of my JavaScript in the assets/javascripts directory.

You should try to create app/assets/javascripts/application2.js.erb (or whatever better name you come up with)

And then put something like this in your app/assets/javascripts/application.js:

//= require application2

And then you can have

<%= javascript_include_tag 'application2' %>

wherever you want - for example in your application.html.erb.

Btw, if you want to customize what's included on a per-view basis you might find content_for useful. Check out this screencast

Ok, about unobtrusive js. It will be just a cocept (HAML):

In your view somewhere

# hotkeys are "Ctrl+C", "Ctrl+A"
-current_user.hotkeys.each do |hotkey|
  %hotkey{ "data-key" => hotkey.key, "data-behavior" => hotkey.fn  }

Then in your application.js

$(document).ready(function(){
  if($("hotkey").length > 0){
    $("hotkey").each{function(this){
      key = $(this).data("key");
      fn  = $(this).data("behavior");
      $(document).bind('keydown', key, fn);
    }}
  }
})

So just the same JS will extract from HTML hotkeys data and then bind it.

As some people have pointed out, the two options are:

• Put your javascript inside the view (and as you say, this doesn't feel quite right).
• Put it in a javascript file. Make a conditional inside your view that includes this javascript file if certain conditions are met.

If you need to pass more instance variables from the controller to your javascript, this gem called gon can make your life easier.

This allows you to use the default asset pipeline using the following javascript:

if(gon.conditional){
  //your embedded js code here
}

If you want to know more about this gem, checkout this railcast where everything gets explained.