Conditionally loading jQuery / Zepto.js in Rails 3

application-ie.coffee

#= require jquery
#= require application.js

application-zepto.coffee

#= require ../../../vendor/assets/javascripts/zepto.min.js
#= require application.js

application.coffee

# normal application js included in both IE and other browsers

applications.html.erb

<!-- application layout -->
<!-- include this at the bottom of the head or body -->
<script>
document.write('<script src="' +
('__proto__' in {} ? '<%= path_to_asset("application-zepto.js") %>' : '<%= path_to_asset("application-ie.js") %>') +
'"><\/script>');
</script>