sosick.js

  request = (opts) =>  {
    return new Promise((resolve, reject) => {
      let xhr = new XMLHttpRequest();
      let params = opts.params;

      xhr.onload = function () {
        if (xhr.status >= 200 && xhr.status < 300) {
          resolve(xhr.response);
        } else {
          reject({
            status: xhr.status,
            statusText: xhr.statusText
          });
        }
      };

      xhr.onerror = function () {
        reject({
          status: xhr.status,
          statusText: xhr.statusText
        });
      };

      if (opts.headers) {
        Object.keys(opts.headers).forEach(function (key) {
          xhr.setRequestHeader(key, opts.headers[key]);
        });
      }

      if (opts.method === 'GET' && params && typeof params === 'object') {

        params = Object.keys(params).map(function (key) {
            return encodeURIComponent(key).replace(/%20/g, '+')  + '=' + encodeURIComponent(params[key]).replace(/%20/g, '+');
          }).join('&');
        
        xhr.open(opts.method, opts.url + '?' + params);
        xhr.send()
      } else {

        xhr.open(opts.method, opts.url);

        if (params && typeof params === 'object') {
          params = Object.keys(params).map(function (key) {
            return encodeURIComponent(key) + '=' + encodeURIComponent(params[key]);
          }).join('&');
        }
        xhr.send(params);
      }
    })
  }