Why is rails using the .js.coffee extension for coffeescript files when they cannot contain javascript code anyway?

Question

I found that to be rather misleading as I thought it suggest that such files could include a mixture of both javascript and coffeescript code. Is there something very fundamental that I am missing?

Answer 1

It's a common practice in Rails for templates to have extensions like .js.coffee, .html.erb, .html.haml, etc.

If I remember correctly Rails interprets these extensions as .[format].[builder] and uses that knowledge to do two things:

1. find proper template by [format] value comparing it with acceptable formats listed in the request's Accept header;
2. find appropriate template processor by [builder] value to parse your template.

Answer 2

And you can include plain javascript if you use backticks.

Something like `function(){ do something };` would work.