function replaceString(id) {

    var control = document.getElementById(id);

    if (control.text != "") {
        control.text = "Username";
    }
}

function getInternetExplorerVersion() {
    var rv = -1;

    try {

        if (navigator.appName == 'Microsoft Internet Explorer') {
            var ua = navigator.userAgent; /* Is this supported in all browsers */
            var re = new RegExp("MSIE ([0-9]{1,}[\.0-9]{0,})");
            if (re.exec(ua) != null)
                rv = parseFloat(RegExp.$1);
        }
    }
    catch (errorObject) { rv = -1; }

    return rv;
}