JavaScript sets IFrame height adaptability (compatible with all major browsers)_javascript skills

function SetIFrameHeight(down) {
var Sys = {};
var ua = navigator.userAgent.toLowerCase();
var s;
(s = ua.match(/msie ([d.] )/)) ? Sys.ie = s[1] :
(s = ua.match(/firefox/([d.] )/)) ? Sys.firefox = s[1] :
(s = ua.match(/chrome/([d.] )/)) ? Sys.chrome = s[1] :
(s = ua.match(/opera.([d.] )/)) ? Sys.opera = s[1] :
(s = ua.match(/version/([d.] ).*safari/)) ? Sys.safari = s[1] : 0;
var pTar = null;
if (document.getElementById) {
pTar = document.getElementById(down);
} else {
eval('pTar=' down ';');
}
pTar.style.display = "block";
if (Sys.ie) {
if (Sys.ie == '9.0') {
pTar.height = pTar.contentWindow.document.body.offsetHeight 15 "px";
pTar.width = pTar.contentWindow.document.body.scrollWidth "px";
} else if (Sys.ie == '8.0') {
debugger;
pTar.height = pTar.Document.body.offsetHeight 15 "px";
pTar.width = pTar.Document.body.scrollWidth "px";
} else {
pTar.height = pTar.Document.body.scrollHeight 25 "px";
pTar.width = pTar.Document.body.scrollWidth "px";
}
}
if (Sys.firefox) {
pTar.height = pTar.contentDocument.body.offsetHeight 15 "px";
pTar.width = pTar.contentDocument.body.scrollWidth "px";
}
if (Sys.chrome) {
pTar.height = pTar.contentDocument.body.offsetHeight;
pTar.width = pTar.contentDocument.body.scrollWidth;
}
if (Sys.opera) {
pTar.height = pTar.contentDocument.body.offsetHeight;
pTar.width = pTar.contentDocument.body.scrollWidth;
}
if (Sys.safari) {
if (pTar.contentDocument.body.offsetHeight <= '186') {
pTar.height = pTar.contentDocument.body.offsetHeight 10;
} else {
pTar.height = pTar.contentDocument.body.offsetHeight;
}
pTar.width = pTar.contentDocument.body.scrollWidth;
}
}