uploader

function postData(
  url, 
  data = {}, 
  {type = 'json', fileKey = 'file', headers = [], onProgress} = {}
) {
    const req = new XMLHttpRequest();
    const formData = new FormData();
  
    req.open('POST', url, true);

    if(data instanceof File) {
      formData.append(fileKey, data, data.name);
      data = formData;
    } else if(type === 'multipart') {
      for(const key in data) {
        formData.append(key, data[key]);
      }
      data = formData;
    } else {
      data = JSON.stringify(data);
      req.setRequestHeader("Content-Type", "application/json;charset=UTF-8");
    }
  
    for(const key in headers) {
      req.setRequestHeader(key, headers[key]);
    }

    return new Promise((res, rej) => {
      req.onload = (e) => {
        if (req.status === 200) {
          res(e);
        } else {
          rej(e);
        }
      }
      
      if(typeof onProgress === 'function') {
        req.upload.onprogress = onProgress;
      }
      
      req.onerror = rej;
      req.onabort = rej;
      req.onabort = rej;
      req.ontimeout = rej;

      req.send(data);
    });
}