从Ext AJAX下载文件

Question

HI I get a tar file in response Text for the Ext AJAX i need to convert that into a file and download. please let me know any way.

Ext.Ajax.request({
             url : 'download.do',
             method:'POST',
             async:false,
             useDefaultXhrHeader: false,
             cors: true,
             params : configRequest.parameters,
             scope : this,
             success : configRequest.success?configRequest.success:function(response){
                    var res = Ext.decode(response.responseText);
                    if(res.result && res.result=='error'){
                        this.ajaxErrorDisplay(res.err);
                    } }, failure : configRequest.failure?configRequest.failure:function(msg){}});