headers(added 1.5)Map
Default: {}A map of additional header key/value pairs to send along with the request. This setting is set before the
beforeSendfunction is called; therefore, any values in the headers setting can be overwritten from within thebeforeSendfunction.ifModifiedBoolean
Default: falseAllow the request to be successful only if the response has changed since the last request. This is done by checking the Last-Modified header. Default value is
false, ignoring the header. In jQuery 1.4 this technique also checks the 'etag' specified by the server to catch unmodified data.