| let crypto = require('crypto') |
| let { urlAlphabet } = require('../url-alphabet/index.cjs') |
| let random = bytes => |
| new Promise((resolve, reject) => { |
| crypto.randomFill(Buffer.allocUnsafe(bytes), (err, buf) => { |
| if (err) { |
| reject(err) |
| } else { |
| resolve(buf) |
| } |
| }) |
| }) |
| let customAlphabet = (alphabet, size) => { |
| let mask = (2 << (31 - Math.clz32((alphabet.length - 1) | 1))) - 1 |
| let step = Math.ceil((1.6 * mask * size) / alphabet.length) |
| let tick = id => |
| random(step).then(bytes => { |
| let i = step |
| while (i--) { |
| id += alphabet[bytes[i] & mask] || '' |
| if (id.length === size) return id |
| } |
| return tick(id) |
| }) |
| return () => tick('') |
| } |
| let nanoid = (size = 21) => |
| random(size).then(bytes => { |
| let id = '' |
| while (size--) { |
| id += urlAlphabet[bytes[size] & 63] |
| } |
| return id |
| }) |
| module.exports = { nanoid, customAlphabet, random } |