问个关于createcdatasection的用法

var xmldoc = new activexobject（"msxml2.domdocument.4.0");
var root;
var cdatasection;
xmldoc.async = false;
xmldoc.resolveexternals = false;
xmldoc.load（"books.xml");
if （xmldoc.parseerror.errorcode != 0) {
   var myerr = xmldoc.parseerror;
   alert（"you have error " + myerr.reason);
} else {
   root = xmldoc.documentelement;
   cdatasection = xmldoc.createcdatasection（"hello world!");
   root.appendchild（cdatasection);
   alert（root.xml);
}