SOURCE

document.write(
  JSON.stringify(
      document.cookie
    .split(';')
    .map(v => v.split('='))
    .reduce((acc, v) => {
      acc[decodeURIComponent(v[0].trim())] = decodeURIComponent(v[1].trim());
      return acc;
    }, {}),
    null,
    2
  )
)