How to pass parameters to IFrame using javascript

I've following code snippet to access http://localhost:80/testsite in IFRAME. It worked fine but as soon as I went to pass the fields value as parameter nothing get happen. I tried directly access the page from browser with parameters so page is behaving fine. I cannot figure out the things after spending a lot of time. I would like to seek your kind patience on this basic question.

code Snippet

function forwardValues(){
    var ordername = Xrm.Page.getAttribute("name").getValue();
    var IFrame = Xrm.Page.ui.controls.get("IFRAME_sendvalue");
    var Url = IFrame.getSrc();

    var params = Url.substr(Url.indexOf("?"));

    var param1 = Url+"?ordername="+ordername;

    IFrame.setSrc(param1);

}