FM / async

/opt/canhelp/node_modules/nanoid/async

Name	Size	Mode	Actions
index.browser.cjs	2692	0644	edit dl rm
index.browser.js	984	0644	edit dl rm
index.cjs	2870	0644	edit dl rm
index.d.ts	1505	0644	edit dl rm
index.js	982	0644	edit dl rm
index.native.js	820	0644	edit dl rm
package.json	233	0644	edit dl rm

Edit: /opt/canhelp/node_modules/nanoid/async/index.cjs (2870B)

let crypto = require('crypto')

let { urlAlphabet } = require('../url-alphabet/index.cjs')

// `crypto.randomFill()` is a little faster than `crypto.randomBytes()`,
// because it is possible to use in combination with `Buffer.allocUnsafe()`.
let random = bytes =>
  new Promise((resolve, reject) => {
    // `Buffer.allocUnsafe()` is faster because it doesn’t flush the memory.
    // Memory flushing is unnecessary since the buffer allocation itself resets
    // the memory with the new bytes.
    crypto.randomFill(Buffer.allocUnsafe(bytes), (err, buf) => {
      if (err) {
        reject(err)
      } else {
        resolve(buf)
      }
    })
  })

let customAlphabet = (alphabet, defaultSize = 21) => {
  // First, a bitmask is necessary to generate the ID. The bitmask makes bytes
  // values closer to the alphabet size. The bitmask calculates the closest
  // `2^31 - 1` number, which exceeds the alphabet size.
  // For example, the bitmask for the alphabet size 30 is 31 (00011111).
  let mask = (2 << (31 - Math.clz32((alphabet.length - 1) | 1))) - 1
  // Though, the bitmask solution is not perfect since the bytes exceeding
  // the alphabet size are refused. Therefore, to reliably generate the ID,
  // the random bytes redundancy has to be satisfied.

// Note: every hardware random generator call is performance expensive,
  // because the system call for entropy collection takes a lot of time.
  // So, to avoid additional system calls, extra bytes are requested in advance.

// Next, a step determines how many random bytes to generate.
  // The number of random bytes gets decided upon the ID size, mask,
  // alphabet size, and magic number 1.6 (using 1.6 peaks at performance
  // according to benchmarks).
  let step = Math.ceil((1.6 * mask * defaultSize) / alphabet.length)

let tick = (id, size = defaultSize) =>
    random(step).then(bytes => {
      // A compact alternative for `for (var i = 0; i < step; i++)`.
      let i = step
      while (i--) {
        // Adding `|| ''` refuses a random byte that exceeds the alphabet size.
        id += alphabet[bytes[i] & mask] || ''
        if (id.length >= size) return id
      }
      return tick(id, size)
    })

return size => tick('', size)
}

let nanoid = (size = 21) =>
  random((size |= 0)).then(bytes => {
    let id = ''
    // A compact alternative for `for (var i = 0; i < step; i++)`.
    while (size--) {
      // It is incorrect to use bytes exceeding the alphabet size.
      // The following mask reduces the random byte in the 0-255 value
      // range to the 0-63 value range. Therefore, adding hacks, such
      // as empty string fallback or magic numbers, is unneccessary because
      // the bitmask trims bytes down to the alphabet size.
      id += urlAlphabet[bytes[size] & 63]
    }
    return id
  })

module.exports = { nanoid, customAlphabet, random }

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