jQuery .ajax() - add query parameters to POST request?

jQuery.param() allows you to serialize the properties of an object as a query string, which you could append to the URL yourself:

$.ajax({
  url: 'http://www.example.com?' + $.param({ paramInQuery: 1 }),
  method: 'POST',
  data: {
    paramInBody: 2
  }
});

Thank you @Ates Goral for the jQuery.ajaxPrefilter() tip. My problem was I could not change the url because it was bound to kendoGrid and the backend web API didn't support kendoGrid's server paging options (i.e. page, pageSize, skip and take). Furthermore, the backend paging options had to be query parameters of a different name. So had to put a property in data to trigger the prefiltering.

var grid = $('#grid').kendoGrid({
    // options here...
    dataSource: {
        transport: {
            read: {
                url: url,
                contentType: 'application/json',
                dataType: 'json',
                type: httpRequestType,
                beforeSend: authentication.beforeSend,
                data: function(data) {
                  // added preFilterMe property
                  if (httpRequestType === 'POST') {
                      return {
                          preFilterMe: true,
                          parameters: parameters,
                          page: data.page,
                          itemsPerPage: data.pageSize,
                      };
                  }

                  return {
                      page: data.page,
                      itemsPerPage: data.pageSize,
                  };
              },
          },
        },
    },
});

As you can see, the transport.read options are the same options for jQuery.ajax(). And in the prefiltering bit:

$.ajaxPrefilter(function(options, originalOptions, xhr) {
    // only mess with POST request as GET requests automatically
    // put the data as query parameters
    if (originalOptions.type === 'POST' && originalOptions.data.preFilterMe) {
        options.url = options.url + '?page=' + originalOptions.data.page 
            + '&itemsPerPage=' + originalOptions.data.itemsPerPage;

        if (originalOptions.data.parameters.length > 0) {
            options.data = JSON.stringify(originalOptions.data.parameters);
        }
    }
});