Jquery插件ajaxfileupload的一次跨域体验

最近在项目中遇到一个非常棘手的问题，就是在为页面设置了document.domain时，ajaxfileupload出现跨域错误，究其原因是页面的domain被设置为***.com时，而ajaxfileupload post to 的页面的域并非根域***.com，而是一个二级的类似abc.***.com的域名，因此会引发无权限的错误。
花了2天的时间终于解决这个问题。
修改后的ajaxfileupload关键代码如下：
var uploadCallback = function(isTimeout) {
      var io = document.getElementById(frameId);
      var execontent = function(){
        try {
          if (io.contentWindow) {
            xml.responseText = io.contentWindow.document.body ? io.contentWindow.document.body.innerHTML: null;
            xml.responseXML = io.contentWindow.document.XMLDocument ? io.contentWindow.document.XMLDocument: io.contentWindow.document;
          } else if (io.contentDocument) {
            xml.responseText = io.contentDocument.document.body ? io.contentDocument.document.body.innerHTML: null;
            xml.responseXML = io.contentDocument.document.XMLDocument ? io.contentDocument.document.XMLDocument: io.contentDocument.document;
          }
        } catch(e) {
          handleError(s, xml, null, e);
        }
        if (xml || isTimeout == "timeout") {
          requestDone = true;
          var status;
          try {
            status = isTimeout != "timeout" ? "success": "error";
            // Make sure that the request was successful or notmodified
            if (status != "error") {
              // process the data (runs the xml through httpData regardless of callback)
              var data = jQuery.uploadHttpData(xml, s.dataType);
              // If a local callback was specified, fire it and pass it the data
              if (s.success) s.success(data, status);
              // Fire the global callback
              if (s.global) jQuery.event.trigger("ajaxSuccess", [xml, s]);
            } else handleError(s, xml, status);
          } catch(e) {
            status = "error";
            handleError(s, xml, status, e);
          }
          // The request was completed
          if (s.global) jQuery.event.trigger("ajaxComplete", [xml, s]);
          // Handle the global AJAX counter
          if (s.global && !--jQuery.active) jQuery.event.trigger("ajaxStop");
          // Process result
          if (s.complete) s.complete(xml, status);
          jQuery(io).unbind();
          setTimeout(function() {
            try {
              jQuery(io).remove();
              jQuery(form).remove();
            } catch(e) {
              handleError(s, xml, null, e);
            }
          },
          100);
          xml = null;
        }
      };
      var crossdomain = !jQuery.browser.msie || document.domain == location.hostname;
      if(!crossdomain) {
        io.src="javascript:try{"
          +"document.domain=window.location.hostname.split('.').reverse().slice(0,2).reverse().join('.');"
          +"parent.document.getElementById('"+ frameId +"').setAttribute('uploaded','uploaded');"
          +"}catch(e){}";
        var timer = window.setInterval(function(){
          try{
            if(io.getAttribute("uploaded") == "uploaded") {
              crossdomain = true;
              window.clearInterval(timer);
              execontent();
            }
          }catch(e){}
        },1000);
      } else {
        execontent();
      }
    }；
解决问题的思路是，如果是IE浏览器并且为当前页面设置了document.domain，那么在创建的iframe提交后，使用iframe的src属性执行一段js代码，从而改变该iframe页面的domain属性，达到同域的目的。

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