History.back in JS

[hpl]

I will make a function, where I need information on the previous web page. Is there a document.location function where I can get this information? If the previous page is uk.htm then the language variable is "english". I have tried the code below, but it doesn't work? I only need information on which site was previous, I don't want to go back to this page.

function validate_website() {
if (history.back() == "uk.htm") {
   language_var == "english"
   }
}
if (history.back() == "d.htm") {
   language_var == "german"
   }
}
}