65 lines
1.8 KiB
JavaScript
65 lines
1.8 KiB
JavaScript
import { webcrypto as crypto } from 'node:crypto'
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import { urlAlphabet as scopedUrlAlphabet } from './url-alphabet/index.js'
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export { urlAlphabet } from './url-alphabet/index.js'
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const POOL_SIZE_MULTIPLIER = 128
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let pool, poolOffset
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function fillPool(bytes) {
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if (!pool || pool.length < bytes) {
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pool = Buffer.allocUnsafe(bytes * POOL_SIZE_MULTIPLIER)
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crypto.getRandomValues(pool)
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poolOffset = 0
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} else if (poolOffset + bytes > pool.length) {
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crypto.getRandomValues(pool)
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poolOffset = 0
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}
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poolOffset += bytes
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}
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export function random(bytes) {
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fillPool((bytes |= 0))
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return pool.subarray(poolOffset - bytes, poolOffset)
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}
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export function customRandom(alphabet, defaultSize, getRandom) {
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let safeByteCutoff = 256 - (256 % alphabet.length)
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if (safeByteCutoff === 256) {
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let mask = alphabet.length - 1
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return (size = defaultSize) => {
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if (!size) return ''
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let id = ''
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while (true) {
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let bytes = getRandom(size)
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let i = size
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while (i--) {
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id += alphabet[bytes[i] & mask]
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if (id.length >= size) return id
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}
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}
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}
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}
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let step = Math.ceil((1.6 * 256 * defaultSize) / safeByteCutoff)
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return (size = defaultSize) => {
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if (!size) return ''
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let id = ''
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while (true) {
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let bytes = getRandom(step)
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let i = step
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while (i--) {
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if (bytes[i] < safeByteCutoff) {
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id += alphabet[bytes[i] % alphabet.length]
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if (id.length >= size) return id
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}
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}
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}
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}
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}
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export function customAlphabet(alphabet, size = 21) {
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return customRandom(alphabet, size, random)
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}
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export function nanoid(size = 21) {
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fillPool((size |= 0))
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let id = ''
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for (let i = poolOffset - size; i < poolOffset; i++) {
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id += scopedUrlAlphabet[pool[i] & 63]
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}
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return id
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}
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