建立XMLHttpRequest对象

p;   str += "<span class=''text''>" + node.nodeValue + "</span><br />";
            break;

        case 7:    // ProcessInstruction
            str += "<?" + node.nodeName;

            var attrs = node.attributes;
            for (var i = 0; i < attrs.length; i++)
                str += createXmlAttribute(attrs[i]);

            str+= "?><br />"
            break;

        case 4:    // CDATA
            str = "<div class=''cdata''><![CDATA[<span class=''cdata-content''>" + 
                node.nodeValue +
            "</span>]" + "]></div>";
            break;

        case 8:    // Comment
            str = "<div class=''comment''><!--<span class=''comment-content''>" + 
                node.nodeValue +
            "</span>--></div>";
            break;

        case 10:
                str = "<div class=''doctype''><!DOCTYPE " + node.name;
                if (node.publicId) {
                    str += " PUBLIC \"" + node.publicId + "\"";
                    if (node.systemId) 
 &nbs