If some of your JavaScripts fail on Internet Explorer, but only in staging or production environments, chances are that JavaScript compression is the culprit.

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By default, Rails 3.2 compresses JavaScript with UglifyJS. I have seen a few cases where this actually breaks functioning JavaScript on IE (one example is the CKEditor Show archive.org snapshot ).

I fixed this by switching to Yahoo's YUI Compressor Show archive.org snapshot .

To do this, do the following:

• replace the uglifier gem with the yui-compressor gem in your Gemfile

• add this line to your application.rb:

  config.assets.js_compressor = :yui