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A module meant to be plugged into the NodeJS connect middleware, which processes the Accept, Accept-Languages, and Accept-Charset HTTP headers to enable you to prioritize the type of data returned down the wire for an HTTP request.

This will modify the Request object, adding a list of strings which are sorted based on the qvalue sent in the HTTP header. These will be mapped to the request object as follows:

  • request.languages - Locale codes from the Accept-Languages header
  • request.charsets - Charset identifiers from the Accept-Charset header
  • request.accepatableTypes - The MIME types the client is willing to accept

These are sorted per the rules in RFC 2616, Section 14.

Expected Values

Consider the following HTTP header from my browser:

Accept-Languages: en-US; q=0.8, en; q=0.5, es

This header indicates the user wants to recieve US English, any English, or any Spanish. Since a q-value is not assigned to Spanish, it will be assigned the q-value 1, per the HTTP/1.1 spec. When sorted on q-value we get the following result in request.languages

['es', 'en-US', 'en']

When preparing to render the response to the client, you can reference this list, shifting results off the front of the list until you encounter a language code you can honor, and returning content customized to your users language of choice. If they do not request a language you can honor, then you can choose to return a default language or an error.

Future versions of this library will include helper methods to perform the lookups against these arrays.