Tomas Bartoli JS AJAX

/**
 * AJAX Library
 *
 * Author: Tomas Bartoli <tomasbartoli1992@gmail.com>
 * Date ...
 */
"use strict";

$ajax.CONF               = {};
$ajax.CONF.SHOW_ERROR    = true;
$ajax.CONF.DEBUG         = true;

function $ajax($params) {
    var _xml_http   = null;
    var _show_error = $ajax.CONF.SHOW_ERROR;
    var _debug      = $ajax.CONF.DEBUG;
    var _data       = [];

    var _init_xml_http = function() {
      if (window.XMLHttpRequest) {
        return new XMLHttpRequest();
      }
      else {
        return new ActiveXObject("Microsoft.XMLHTTP");
      }
    }

    if (!$params.url || !$params.type) {
      if (_show_error) {
        if (!$params.url) {
          alert("$ajax::show_error: Url parameter is not optional.");
        }
        else {
          alert("$ajax::show_error: Type parameter is not optional.");
        }
      }

      return;
    }

    if (!$params.method) {
      $params.method = true;
    }

    _xml_http = _init_xml_http();
    _xml_http.onreadystatechange = function() {
      if (_xml_http.readyState == 4 && _xml_http.status == 200) {
        if ($params.success) {
          $params.success(_xml_http.responseText, _xml_http.readyState);

          if (_debug) {
            console.log("$ajax::debug: Response Data:" + _xml_http.responseText);
          }
        }
      }
      else if (_show_error) {
        alert("$ajax::show_error: FailureResponse\nState:" + _xml_http.readyState + "\nStatus:" + _xml_http.status);
      }
    }

    if ($params.data === 'object') {
      for (var key in $params.data) {
        var _tmp = $params.data[key];
        if(Object.prototype.toString.call(_tmp) == "[object Array]") {
          for(var i = 0, j = _tmp.length; i < j; i++) {
            _data.push(encodeURIComponent(key) + "[]=" + encodeURIComponent(_tmp[i]));
          }
        }
        else {
          _data.push(encodeURIComponent(key) + "=" + encodeURIComponent(_tmp));
        }
      }
      _data = _data.join("&");
    }

    switch ($params.type) {
      case "GET":
        _xml_http.open("GET", $params.url + "?" + _data, $params.method);
        _xml_http.send();
      break;

      case "POST":
        _xml_http.open("GET", $params.url, $params.method);
        _xml_http.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
        _xml_http.send(_data);
      break;

      default:
        if (_show_error) {
          alert("$ajax::show_error: Parameter allowed: 'GET' or 'POST'.");
        }
      break;
    }
}