Function generateShortId

packages/utils/src/id.ts:46–67

(size = 21, alphabet: string = URL_SAFE_ALPHABET)

 * @returns A random string drawn from the alphabet
 */
export function generateShortId(size = 21, alphabet: string = URL_SAFE_ALPHABET): string {
  const alphabetLength = alphabet.length
  if (alphabetLength < 2 || alphabetLength > 256) {
    throw new Error('generateShortId alphabet length must be between 2 and 256')
  }

  const mask = (2 << (31 - Math.clz32((alphabetLength - 1) | 1))) - 1
  const step = Math.ceil((1.6 * mask * size) / alphabetLength)

  let id = ''
  while (id.length < size) {
    const bytes = new Uint8Array(step)
    crypto.getRandomValues(bytes)
    for (let i = 0; i < step && id.length < size; i++) {
      const index = bytes[i] & mask
      if (index < alphabetLength) {
        id += alphabet[index]
      }
    }
  }
  return id
}