ie-9 以下ajax无法跨域的问题。只要add:jQuery.support.cors=true;即可

if (!jQuery.support.cors && window.XDomainRequest) {
    var httpRegEx = /^https?:\/\//i;
    var getOrPostRegEx = /^get|post$/i;
    var sameSchemeRegEx = new RegExp('^'+location.protocol, 'i');
    var xmlRegEx = /\/xml/i;
    
    // ajaxTransport exists in jQuery 1.5+
    jQuery.ajaxTransport('text html xml json', function(options, userOptions, jqXHR){
        // XDomainRequests must be: asynchronous, GET or POST methods, HTTP or HTTPS protocol, and same scheme as calling page
        if (options.crossDomain && options.async && getOrPostRegEx.test(options.type) && httpRegEx.test(userOptions.url) && sameSchemeRegEx.test(userOptions.url)) {
            var xdr = null;
            var userType = (userOptions.dataType||'').toLowerCase();
            return {
                send: function(headers, complete){
                    xdr = new XDomainRequest();
                    if (/^\d+$/.test(userOptions.timeout)) {
                        xdr.timeout = userOptions.timeout;
                    }
                    xdr.ontimeout = function(){
                        complete(500, 'timeout');
                    };
                    xdr.onload = function(){
                        var allResponseHeaders = 'Content-Length: ' + xdr.responseText.length + '\r\nContent-Type: ' + xdr.contentType;
                        var status = {
                            code: 200,
                            message: 'success'
                        };
                        var responses = {
                            text: xdr.responseText
                        };
                       
                                try {
                                    if (userType === 'json') {
                                        try {
                                            responses.json = JSON.parse(xdr.responseText);
                                        } catch(e) {
                                            status.code = 500;
                                            status.message = 'parseerror';
                                            //throw 'Invalid JSON: ' + xdr.responseText;
                                        }
                                    } else if ((userType === 'xml') || ((userType !== 'text') && xmlRegEx.test(xdr.contentType))) {
                                        var doc = new ActiveXObject('Microsoft.XMLDOM');
                                        doc.async = false;
                                        try {
                                            doc.loadXML(xdr.responseText);
                                        } catch(e) {
                                            doc = undefined;
                                        }
                                        if (!doc || !doc.documentElement || doc.getElementsByTagName('parsererror').length) {
                                            status.code = 500;
                                            status.message = 'parseerror';
                                            throw 'Invalid XML: ' + xdr.responseText;
                                        }
                                        responses.xml = doc;
                                    }
                                } catch(parseMessage) {
                                    throw parseMessage;
                                } finally {
                                    complete(status.code, status.message, responses, allResponseHeaders);
                                }
                            };
                            xdr.onerror = function(){
                                complete(500, 'error', {
                                    text: xdr.responseText
                                });
                            };
                            xdr.open(options.type, options.url);
                            //xdr.send(userOptions.data);
                            xdr.send();
                        },
                        abort: function(){
                            if (xdr) {
                                xdr.abort();
                            }
                        }
                    };
                }
            });
    };

add:　　jQuery.support.cors = true;