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