Acquire Asset Path from JavaScript

Checkout the js_assets(Javascript helper in rails projects) gem. I think it is precisely what you need.

From the documentation:

Get the path to the template app/assets/javascripts/rubrics/views/index.html in javascript: var path = asset_path('rubrics/views/index.html')

Why not add a data attribute for the path inside an element in your .erb file and then retrieve that with JQuery?

inside some_template.html.erb

<%= content_tag(:div, "", id: 'some-id', data:{path_to_asset: asset_path("some_image.png")}) %>

then in some_javascript.js

var assetPath = $("#some-id").data("pathToAsset");

For those using HAML you can do:

:javascript
   var assetPath = "#{asset_path('some_image.jpg')}";

In the Rails Asset Pipeline guide, they give an example of coding assets in your stylesheets by preprocessing the stylesheets with ERB. You can use the same technique with JavaScript, assuming you tack an .erb to the end of the filename:

var someAssetPath = "<%= asset_path('some_image.png') %>";