javascript response Javascript response header

$.ajax({
    type: 'HEAD', // 获取头信息，type=HEAD即可
    url : window.location.href,
    //url:"http://device.qq.com/cgi-bin/device_cgi/remote_bind_get_Verify",
    complete: function( xhr,data ){
        // 获取相关Http Response header
        var wpoInfo = {
            // 服务器端时间
            "date" : xhr.getResponseHeader('Date'),
            // 如果开启了gzip，会返回这个东西
            "contentEncoding" : xhr.getResponseHeader('Content-Encoding'),
            // keep-alive ？ close？
            "connection" : xhr.getResponseHeader('Connection'),
            // 响应长度
            "contentLength" : xhr.getResponseHeader('content-length'),
            // 服务器类型，apache？lighttpd？
            "server" : xhr.getResponseHeader('Server'),
            "vary" : xhr.getResponseHeader('Vary'),
            "transferEncoding" : xhr.getResponseHeader('Transfer-Encoding'),
            // text/html ? text/xml?
            "contentType" : xhr.getResponseHeader('Content-Type'),
            "cacheControl" : xhr.getResponseHeader('Cache-Control'),
            // 生命周期？
            "exprires" : xhr.getResponseHeader('Exprires'),
            "lastModified" : xhr.getResponseHeader('Last-Modified')
        };
        console.log(xhr.getAllResponseHeaders());
    }
});