jquery .unload problem in IE

I have the following code that works flawlessy in FF, but in IE I get an error that says "invalid property value"

The code in questions is as follows:

pageOpen = new Date();

dropper = new Image();

$(window).unload(function() {

  pageClose = new Date();

  sionara = (pageOpen.getTime() - pageClose.getTime())/-1000;

  dropper.src = "http://redacted.domain.com/1/%%PAGE%%/1%%REALRAND%%@x80&XE&ABC_Tim开发者_如何学运维eSpent="+sionara+"_seconds&XE";

  alert("close " + sionara);

});

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your dropper source seems wrong. why do you have so many % and @ in it?