nostr-tools/nip13.ts

/** Get POW difficulty from a Nostr hex ID. */
export function getPow(hex: string): number {
  let count = 0

  for (let i = 0; i < hex.length; i++) {
    const nibble = parseInt(hex[i], 16)
    if (nibble === 0) {
      count += 4
    } else {
      count += Math.clz32(nibble) - 28
      break
    }
  }

  return count
}