var http_request = false;
function makeRequest(url, parameters) {
  http_request = false;
  if (window.XMLHttpRequest) { // Mozilla, Safari,...
     http_request = new XMLHttpRequest();
     if (http_request.overrideMimeType) {
     	// set type accordingly to anticipated content type
        //http_request.overrideMimeType('text/xml');
        http_request.overrideMimeType('text/html');
     }
  } else if (window.ActiveXObject) { // IE
     try {
        http_request = new ActiveXObject("Msxml2.XMLHTTP");
     } catch (e) {
        try {
           http_request = new ActiveXObject("Microsoft.XMLHTTP");
        } catch (e) {}
     }
  }
  if (!http_request) {
     alert('Cannot create XMLHTTP instance');
     return false;
  }
  http_request.onreadystatechange = alertContents;
  http_request.open('GET', url + parameters, true);
  http_request.send(null);
}

function alertContents() {
  if (http_request.readyState == 4) {
     if (http_request.status == 200) {
        //alert(http_request.responseText);
        result = http_request.responseText;
		// convert string to XML object
		var xmlobject = (new DOMParser()).parseFromString(result, "text/xml");

		// get a reference to the root-element "rss"
		var root = xmlobject.getElementsByTagName('answer')[0];
		// get reference to "channel" element
		var message = root.getElementsByTagName("message")[0].firstChild.nodeValue;
		var targetid = root.getElementsByTagName("targetid")[0].firstChild.nodeValue;
        document.getElementById(targetid).innerHTML = message;
        document.getElementById(targetid).style.display = "block";
        //$("#nicknameError").html('<img src="/gfx/er.gif"> '+ message +"<br/>");
		//$("#nickname").css("border", "1px solid #FF7B5A");
     } else {
        alert('There was a problem with the request.');
     }
  }
}

function checkNickname(nickname) {
	var getstr = "?target=nicknameError&form=register&check=nickname&nickname=" + nickname;

	makeRequest('json.php', getstr);
}

function get(obj) {
  var getstr = "?";
  for (i=0; i<obj.childNodes.length; i++) {
     if (obj.childNodes[i].tagName == "INPUT") {
        if (obj.childNodes[i].type == "text") {
           getstr += obj.childNodes[i].name + "=" + obj.childNodes[i].value + "&";
        }
        if (obj.childNodes[i].type == "checkbox") {
           if (obj.childNodes[i].checked) {
              getstr += obj.childNodes[i].name + "=" + obj.childNodes[i].value + "&";
           } else {
              getstr += obj.childNodes[i].name + "=&";
           }
        }
        if (obj.childNodes[i].type == "radio") {
           if (obj.childNodes[i].checked) {
              getstr += obj.childNodes[i].name + "=" + obj.childNodes[i].value + "&";
           }
        }
     }
     if (obj.childNodes[i].tagName == "SELECT") {
        var sel = obj.childNodes[i];
        getstr += sel.name + "=" + sel.options[sel.selectedIndex].value + "&";
     }

  }
  makeRequest('json.php', getstr);
}