Get the response size in TypeScript of a request payload

responseSize.ts

// https://github.com/vercel/vercel/issues/3825#issuecomment-961295566
function formatBytes(bytes: number, decimals = 2) {
  if (bytes === 0) return '0 Bytes'

  const k = 1024
  const dm = decimals < 0 ? 0 : decimals
  const sizes = ['Bytes', 'KB', 'MB', 'GB', 'TB', 'PB', 'EB', 'ZB', 'YB']

  const i = Math.floor(Math.log(bytes) / Math.log(k))

  return parseFloat((bytes / Math.pow(k, i)).toFixed(dm)) + ' ' + sizes[i]
}

export function responseSize(payload: any) {
  const rs = Buffer.byteLength(JSON.stringify(payload), 'utf-8')
  console.log('FINAL Response', rs, formatBytes(rs))
}