gistfile1.js

  $.fn.ajaxThatForm = function(opts){
    this.each(function(i,el){
      var formParams = {
        action : $(this).attr("action"),
        method : $(this).attr("method")
      };

      $.extend(formParams,opts);
      var formData = new FormData();

      $("input",el).each(function(i,formEl){
        fel = $(formEl);
        if(fel.is("[type=file]")){
          if(fel[0].files.length == 0){
            return;
          }

          if(fel[0].files.length == 1){
            formData.append(
              fel.attr('name'),
              fel[0].files[0]);
          }
          else
          {
            for(x in fel[0].files){
              formData.append(
                fel.attr('name') + "-" + x,
                fel[0].files[x]);
            }
          }
        }
        else
        {
          formData.append(fel.attr('name'),fel.val());
        }
      });
      $.ajax({
        url: formParams.action,
        data: formData,
        cache: false,
        contentType: false,
        processData: false,
        async: true,
        type: formParams.method,
        success: function(data){
          alert(data);
        }});
    });

  return this;
}