gistfile1.txt

putFile(url: string, file: any) {
    return new Promise<FileUploadResponse>((resolve, reject) => {
      const xhr = new XMLHttpRequest()
      xhr.onreadystatechange = function() {
        if (xhr.readyState === 4) {
          if (xhr.status === 200) {
            resolve ({ok: true, status: xhr.status, message: xhr.responseText});
          } else {
            reject({ok: false, status: xhr.status, message: xhr.responseText});
          }
        }
      }
      xhr.open('PUT', url)
      xhr.setRequestHeader('Content-Type', file.type);
      xhr.send(file);
    });
  }