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GitHub User: brainlid
This is late, but a tip for others...
Assuming the reason is for viewing it yourself in a browser, the easiest (and general fix) is to use a nice browser plugin. There are two plugins both named "JSONView" for Chrome and Firefox. I use the Chrome one. Very nice tool for viewing JSON API responses.
While deleting bootstrap.js.coffee stops the error, it also makes it so those Bootstrap features won't be available in your application.
//= require jquery
//= require jquery_ujs
//= require twitter/bootstrap
//= require bootstrap
//= require_tree .
The key is to add the "twitter/bootstrap" before the "bootstrap". Then the functions should be available. Check your page source in development mode to verify that a number of bootstrap js files get included.