46 lines
1.3 KiB
JavaScript
46 lines
1.3 KiB
JavaScript
|
import crypto from 'crypto'
|
||
|
|
import { urlAlphabet } from './url-alphabet/index.js'
|
||
|
|
const POOL_SIZE_MULTIPLIER = 128
|
||
|
|
let pool, poolOffset
|
||
|
|
let fillPool = bytes => {
|
||
|
|
if (!pool || pool.length < bytes) {
|
||
|
|
pool = Buffer.allocUnsafe(bytes * POOL_SIZE_MULTIPLIER)
|
||
|
|
crypto.randomFillSync(pool)
|
||
|
|
poolOffset = 0
|
||
|
|
} else if (poolOffset + bytes > pool.length) {
|
||
|
|
crypto.randomFillSync(pool)
|
||
|
|
poolOffset = 0
|
||
|
|
}
|
||
|
|
poolOffset += bytes
|
||
|
|
}
|
||
|
|
let random = bytes => {
|
||
|
|
fillPool((bytes -= 0))
|
||
|
|
return pool.subarray(poolOffset - bytes, poolOffset)
|
||
|
|
}
|
||
|
|
let customRandom = (alphabet, defaultSize, getRandom) => {
|
||
|
|
let mask = (2 << (31 - Math.clz32((alphabet.length - 1) | 1))) - 1
|
||
|
|
let step = Math.ceil((1.6 * mask * defaultSize) / alphabet.length)
|
||
|
|
return (size = defaultSize) => {
|
||
|
|
let id = ''
|
||
|
|
while (true) {
|
||
|
|
let bytes = getRandom(step)
|
||
|
|
let i = step
|
||
|
|
while (i--) {
|
||
|
|
id += alphabet[bytes[i] & mask] || ''
|
||
|
|
if (id.length === size) return id
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
let customAlphabet = (alphabet, size = 21) =>
|
||
|
|
customRandom(alphabet, size, random)
|
||
|
|
let nanoid = (size = 21) => {
|
||
|
|
fillPool((size -= 0))
|
||
|
|
let id = ''
|
||
|
|
for (let i = poolOffset - size; i < poolOffset; i++) {
|
||
|
|
id += urlAlphabet[pool[i] & 63]
|
||
|
|
}
|
||
|
|
return id
|
||
|
|
}
|
||
|
|
export { nanoid, customAlphabet, customRandom, urlAlphabet, random }
|