How to manually set REFERER header in Javascript?

You can use Object.defineProperty on the document object for the referrer property:

Object.defineProperty(document, "referrer", {get : function(){ return "my new referrer"; }});

Unfortunately this will not work on any version of safari <=5, Firefox < 4, Chrome < 5 and Internet Explorer < 9 as it doesn’t allow defineProperty to be used on dom objects.