Google Maps API 2.0解析(15-GXslt和GXmlHttp实现AJAX)

        这次Google将AJAX的很多内容从Maps API之中分离出去，带一个独立的GAjax项目中去了，所以这些代码都是简单常规的代码。

        //GXml的静态方法value,返回指定XML节点的值
        function value(a)
        {
            if(!a)
            {
                return""
            }
            var b="";
            if(a.nodeType==3||a.nodeType==4||a.nodeType==2)
            {
                b+=a.nodeValue
            }
            else if(a.nodeType==1||a.nodeType==9||a.nodeType==11)
            {
                for(var c=0;c<a.childNodes.length;++c)
                {
                    b+=arguments.callee(a.childNodes[c])
                }
            }
            return b
        }
        //GXmlHttp的静态函数create，返回一个xmlhttp对象
        function create()
        {
            try
            {
                if(typeof ActiveXObject!="undefined")
                {
                    return new ActiveXObject("Microsoft.XMLHTTP")
                }
                else if(window.XMLHttpRequest)
                {
                    return new XMLHttpRequest()
                }
            }
            catch(a)
            {
            }
            return null
        }
        //下载指定的xml文档
        function GDownloadUrl(url,onload,usePost,contentType)
        {
            var xmlhttp=create();//获取一个xmlhttp对象
            if(!xmlhttp)return false;
            xmlhttp.onreadystatechange=function()
            {
                if(xmlhttp.readyState==4)
                {
                    onload(xmlhttp.responseText,xmlhttp.status);
                    xmlhttp.onreadystatechange=nullFunction
                }
            };
            if(usePost)
            {
                xmlhttp.open("POST",url,true);
                var f=contentType;
                if(!f)
                {
                    f="application/x-www-form-urlencoded"
                }
                e.setRequestHeader("Content-Type",f);
                e.send(usePost)
            }
            else
            {
                e.open("GET",url,true);
                e.send(null)
            }
            return true
        }
        function nullFunction()
        {
        };
        //GXml的静态方法parse,参数a是xml字符串
        function parse(a)
        {
            if(typeof ActiveXObject!="undefined"&&typeof GetObject!="undefined")//IE模式
            {
                var b=new ActiveXObject("Microsoft.XMLDOM");
                b.loadXML(a);
                return b
            }
            if(typeof DOMParser!="undefined")//Firefox模式
            {
                return(new DOMParser()).parseFromString(a,"text/xml")
            }
            return CreateElement("div",null)
        }
        //进行XSLT转化的类，构造函数是一个XSLT的xmlNode
        function GXslt(a)
        {
            this.xsltNode=a
        }
        GXslt.prototype.transformToHtml=function(a,b)
        {
            if(a.transformNode)//浏览器是否支持XSLT转化(IE模式)
            {
                setInnerHTML(b,a.transformNode(this.xsltNode));
                return true
            }
            else if(XSLTProcessor&&XSLTProcessor.prototype.jf)//(FireFox模式的XSLT转化，这一段我也不是太懂)
            {
                var c=new XSLTProcessor();
                c.jf(this.mh);//jf究竟是一个什么方法呢？浏览器集成的，还是Google的AJAX里面提供的？
                var d=c.transformToFragment(a,window.document);
                removeNodeChildren(b);
                b.appendChild(d);
                return true
            }
            else
            {
                return false
            }
        };