Request-Function for Widgets:

Syntax:

  ajax(file, [func_target], [use_req_num])
  - file:        server address (for example: "http://example.com/test.php")
  - func_target: optional, if func_target is set, the response of the request
                 will be send to the function as argument
  - use_req_num: optional, if use_req_num is set, the function will check
                 whether a response was sent


Examples:

  1. Example:
    ajax('http://example.com/');
    // a request will be send to http://example.com
  
  
  2. Example:
    function get_resp(resp) {
      alert(resp);
    }
    ajax('http://example.com/',get_resp);
    // The response will be given to function get_resp.
    // So the content of the website will be displayed in the alert box.

  3. Example:
    function get_resp(resp) {
      alert(resp);
    }
    ajax('http://example.com/',get_resp,true);
    // Same like before but if a connection error occurs or the website
    // returns an empty response the error function is called after 10 seconds

  4. Example:
    function get_resp(argument1, resp) { // Currying adds the response as last argument
      alert(argument1 + resp);
    }
    ajax('http://example.com/',get_resp.curry('another argument for the function'),true);
    // Same like before but another Argument is passed to the target function


/*******************************************************************************
************************************* CODE *************************************
*******************************************************************************/

var req_num = 0; // req_num checks whether the connection-ID is still valid

function checkAjaxError(tmp_req_num) { // the function which will be called after 10 sec and checks if a response was sent
  if (req_num == tmp_req_num) {
    req_num++;
    alert('Error! Missing or slow Internet connection.');
    /*

      Here you can insert the code, which will be run when an error occurs

    */
  }
}

function ajax(file, func_target, use_req_num) { // use_req_num if switchLoading is used
  var tmp_ajax_obj = (window.XMLHttpRequest) ? new XMLHttpRequest() : new ActiveXObject('Microsoft.XMLHTTP'); // runs in IE too ;)
  tmp_ajax_obj.open('post', file, true);     // post => no browser-cache
  req_num++;
  var tmp_req_num = req_num;
  if (func_target) {
    if (use_req_num)
      setTimeout('checkAjaxError('+tmp_req_num+');',10000); // after 10 secs => connection error, change the time to get the error earlier
    tmp_ajax_obj.onreadystatechange = function(){
      if(tmp_ajax_obj.readyState == 4 && (!use_req_num || tmp_req_num == req_num) && tmp_ajax_obj.responseText != '') {
        req_num++;
        func_target(tmp_ajax_obj.responseText); // target function is called
      }
    }
  }
  tmp_ajax_obj.send(null);
}


/* Thanks to molily:
** http://forum.de.selfhtml.org/archiv/2009/7/t188707/#m1256395 */
Function.prototype.curry = (function (slice) { // Currying for JavaScript
  return function () {
    var func = this, args = slice.apply(arguments);
    return function () {
      return func.apply(this, args.concat(slice.apply(arguments)));
    };
  };
})(Array.prototype.slice);