window.$httpGetParams = function(data) {
  var arr = [];
  for (var param in data) {
    arr.push(encodeURIComponent(param) + "=" + encodeURIComponent(data[param]));
  }
  return arr.join("&");
};

window.$http = function(options) {
  options = options || {};
  options.type = (options.type || "GET").toUpperCase();
  options.dataType = options.dataType || "json";
  if (options.async === undefined) {
    options.async = true;
  }
  var params = window.$httpGetParams(options.data);
  var xhr;
  if (window.XMLHttpRequest) {
    xhr = new XMLHttpRequest();
  } else {
    xhr = new ActiveXObject("Microsoft.XMLHTTP");
  }
  xhr.onreadystatechange = function() {
    if (xhr.readyState == 4) {
      var status = xhr.status;
      if (status >= 200 && status < 300) {
        if (options.dataType === "json") {
          options.success && options.success(JSON.parse(xhr.responseText));
        } else {
          options.success && options.success(xhr.responseText);
        }
      } else {
        options.error && options.error(status);
      }
    }
  };
  if (options.type == "GET") {
    xhr.open("GET", options.url + "?" + params, options.async);
    xhr.send(null);
  } else if (options.type == "POST") {
    xhr.open("POST", options.url, options.async);
    xhr.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
    xhr.send(params);
  } else {
    xhr.open(options.type, options.url, options.async);
    xhr.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
    xhr.send(params);
  }
};