chrome safari javascript jquery back

Is there anything particular to chrome or safari that开发者_JS百科 would make a javascript/jquery script work on the first page load, but then when the user hits the back button after navigating the site, it causes select boxes to be selected?

Here is the code. Apologizes before hand for the lack of conventions. I had to get this up quick:

http://www.mailcanarias.com/index.php

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I believe that's because (at least Safari) auto-refills forms when you go back