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Include the following text in your HTML to see the client's environmental variables:

Which will appear as:
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You can access any of the variables in JavaScript space by calling something like the following:
Note: if the environmental variable has anything other than letters and dashes in it, it will be turned into underscores. Also note I removed the HTTP_REFERER since it will always be whatever page you're calling this from as that's what my server sees (you can call the real referring URL from JavaScript space).