兼容IE/Firefox/Opera/Safari的检测页面装载完毕的脚本Ext.onReady的实现

<script type="text/javascript"><!--
function GOOGLEResize(){
alert(1);
}
var ua=navigator.userAgent.toLowerCase();
var isStrict=document.compatMode=="CSS1Compat",
isOpera=ua.indexOf("opera")>-1,
isSafari=(/webkit|khtml/).test(ua),
isIE=ua.indexOf("msie")>-1,
isIE7=ua.indexOf("msie 7")>-1,
isGecko=!isSafari&&ua.indexOf("gecko")>-1,
isBorderBox=isIE&&!isStrict,
isWindows=(ua.indexOf("windows")!=-1||ua.indexOf("win32")!=-1),
isMac=(ua.indexOf("macintosh")!=-1||ua.indexOf("mac os x")!=-1),
isLinux=(ua.indexOf("linux")!=-1),
isSecure=window.location.href.toLowerCase().indexOf("https")===0;
if(isGecko || isOpera) {
    document.addEventListener("DOMContentLoaded", GOOGLEResize, false);
}else if(isIE){
    document.write("<s"+'cript id="ie-deferred-loader" defer="defer" src="/'+'/:"></s'+"cript>");
    var defer = document.getElementById("ie-deferred-loader");
    defer.onreadystatechange = function(){
        if(this.readyState == "complete"){
            GOOGLEResize();
        }
    };
}else if(Ext.isSafari){
    docReadyProcId = setInterval(function(){
        var rs = document.readyState;
        if(rs == "complete") {
            GOOGLEResize();
         }
    }, 10);
}else{
window.onload=GOOGLEResize;
}
// --></script>