module.exports = function (url) {
  this.orginurl = url;
  this.baseurl = url;
  this.checked = false;
  this.addKV = function (key, value) {
    if (typeof (value) == 'undefined') {
      return this;
    }
    this._checkurl();
    var str = encodeURIComponent(key) + '=' + encodeURIComponent(value);
    this.baseurl += str;
    return this;
  };

  this.clear = function () {
    this.baseurl = this.orginurl;
    this.checked = false;
  };

  this._checkurl = function () {
    if (!this.checked) {
      if (this.baseurl.indexOf("?") == -1) {
        this.baseurl += "?";
      } else {
        this.baseurl += "&";
      }
      this.checked = true;
    } else {
      this.baseurl += "&";
    }

  };
};