Question

I’m use Rails 3.2 built in sprockets functionality to compile static assets. Is it possible to compile javascript with environment specific variables?

So I would like to do something like this

/assets/javascripts/myfile.js

---

 //lots of code
 script.src =
        ('https:' == document.location.protocol ? 'https://' : 'http://') +
                'some.metrics.site/projects/<%=ENV_SPECIFIC_TOKEN%>.js';
  //lots of other code

Answer 1

Sprockets lets you append any number of preprocessors to a filename. Add a .erb to the end, and it will be first interpreted as ERB and then output as a JavaScript file.

mv assets/javascripts/myfile.js assets/javascripts/myfile.js.erb

Check out the Rails Asset Pipeline guide on JavaScript/CoffeeScript and ERB.