old_contents: import Config from '../constants/Config';
  
  const Buffer = require('buffer').Buffer;
  
  const requestLocation = `${Config.SERVER}${Config.API_PATH}`;
  
  function _getQueryParametersString(queryParameters) {
    let queryParametersString;
    queryParametersString = queryParameters[0];
    for (let i = 1; i < queryParameters.length; i++) {
      queryParametersString += `,${queryParameters[i]}`;
    }
    return queryParametersString;
  }
  
  function _getParametersString(parameters) {
    let parametersString;
    parametersString = `?${parameters[0]}`;
    for (let i = 1; i < parameters.length; i++) {
      parametersString += `&${parameters[i]}`;
    }
    return parametersString;
  }
  
  function _createAuthorizationHeader() {
    const userLoggedIn = true;
    if (!userLoggedIn) {
      return null
    }
  
    const userId = Config.TEST_USER_ID;
    const secret = Config.TEST_SECRET;
    const hash = new Buffer(`${userId}:${secret}`).toString('base64');
    return { Authorization: `Basic ${hash}` };
  }
  
  class DataLoader {
    static createRequestUrl(apiUrl, queryParameters, parameters) {
      let requestUrl = requestLocation;
  
      if (!apiUrl.startsWith('/')) requestUrl += '/';
      requestUrl = requestUrl + apiUrl;
  
      if (!requestUrl.endsWith('/')) requestUrl += '/';
  
      if (queryParameters !== null && queryParameters.length !== 0 && queryParameters[0] !== null) {
        requestUrl += _getQueryParametersString(queryParameters);
      }
  
      if (parameters !== null && parameters.length !== 0 && parameters[0] !== null) {
        requestUrl += _getParametersString(parameters);
      }
  
      return requestUrl;
    }
  
    static makeRequest(requestUrl, onSuccess, onError, initializer) {
      let authorizationHeader = _createAuthorizationHeader();
      fetch(requestUrl, { headers: authorizationHeader }) //{ Authorization: `Basic ${hash}` } })
        .then((response) => { return response.json() })
        .then((responseData) => { return responseData })
        .then((data) => {
          let response = data.return;
          if (initializer != null) {
            response = initializer(response);
          }
          onSuccess(response);
        })
        .catch((error) => {
          if (onError != null) {
            onError(error);
          } else {
            console.log(error);
          }
        })
        .done();
    }
  }
  
  export default DataLoader;
  
new_contents: import Config from '../constants/Config';
  
  const Buffer = require('buffer').Buffer;
  
  const requestLocation = `${Config.SERVER}${Config.API_PATH}`;
  
  function _getQueryParametersString(queryParameters) {
    let queryParametersString;
    queryParametersString = queryParameters[0];
    for (let i = 1; i < queryParameters.length; i++) {
      queryParametersString += `,${queryParameters[i]}`;
    }
    return queryParametersString;
  }
  
  function _getParametersString(parameters) {
    let parametersString;
    parametersString = `?${parameters[0]}`;
    for (let i = 1; i < parameters.length; i++) {
      parametersString += `&${parameters[i]}`;
    }
    return parametersString;
  }
  
  function _createAuthorizationHeader() {
    const userLoggedIn = true;
    if (!userLoggedIn) {
      return null
    }
  
    const userId = Config.TEST_USER_ID;
    const secret = Config.TEST_SECRET;
    const hash = new Buffer(`${userId}:${secret}`).toString('base64');
    return { Authorization: `Basic ${hash}` };
  }
  
  class DataLoader {
    static createRequestUrl(apiUrl, queryParameters, parameters) {
      let requestUrl = requestLocation;
  
      if (!apiUrl.startsWith('/')) requestUrl += '/';
      requestUrl = requestUrl + apiUrl;
  
      if (!requestUrl.endsWith('/')) requestUrl += '/';
  
      if (queryParameters !== null && queryParameters.length !== 0 && queryParameters[0] !== null) {
        requestUrl += _getQueryParametersString(queryParameters);
      }
  
      if (parameters !== null && parameters.length !== 0 && parameters[0] !== null) {
        requestUrl += _getParametersString(parameters);
      }
  
      return requestUrl;
    }
  
    static makeRequest(requestUrl, onSuccess, onError, initializer) {
      let authorizationHeader = _createAuthorizationHeader();
      fetch(requestUrl, { headers: authorizationHeader })
        .then((response) => { return response.json() })
        .then((responseData) => { return responseData })
        .then((data) => {
          let response = data.return;
          if (initializer != null) {
            response = initializer(response);
          }
          onSuccess(response);
        })
        .catch((error) => {
          if (onError != null) {
            onError(error);
          } else {
            console.log(error);
          }
        })
        .done();
    }
  }
  
  export default DataLoader;
  
subject: remove redundant comment