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- // This file replaces `index.js` in bundlers like webpack or Rollup,
- // according to `browser` config in `package.json`.
- import { urlAlphabet } from './url-alphabet/index.js'
- if (false) {
- // All bundlers will remove this block in the production bundle.
- if (
- typeof navigator !== 'undefined' &&
- navigator.product === 'ReactNative' &&
- typeof crypto === 'undefined'
- ) {
- throw new Error(
- 'React Native does not have a built-in secure random generator. ' +
- 'If you don’t need unpredictable IDs use `nanoid/non-secure`. ' +
- 'For secure IDs, import `react-native-get-random-values` ' +
- 'before Nano ID.'
- )
- }
- if (typeof msCrypto !== 'undefined' && typeof crypto === 'undefined') {
- throw new Error(
- 'Import file with `if (!window.crypto) window.crypto = window.msCrypto`' +
- ' before importing Nano ID to fix IE 11 support'
- )
- }
- if (typeof crypto === 'undefined') {
- throw new Error(
- 'Your browser does not have secure random generator. ' +
- 'If you don’t need unpredictable IDs, you can use nanoid/non-secure.'
- )
- }
- }
- let random = bytes => crypto.getRandomValues(new Uint8Array(bytes))
- let customRandom = (alphabet, size, getRandom) => {
- // 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).
- // `Math.clz32` is not used, because it is not available in browsers.
- let mask = (2 << (Math.log(alphabet.length - 1) / Math.LN2)) - 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).
- // `-~f => Math.ceil(f)` if f is a float
- // `-~i => i + 1` if i is an integer
- let step = -~((1.6 * mask * size) / alphabet.length)
- return () => {
- let id = ''
- while (true) {
- let bytes = getRandom(step)
- // A compact alternative for `for (var i = 0; i < step; i++)`.
- let j = step
- while (j--) {
- // Adding `|| ''` refuses a random byte that exceeds the alphabet size.
- id += alphabet[bytes[j] & mask] || ''
- if (id.length === size) return id
- }
- }
- }
- }
- let customAlphabet = (alphabet, size) => customRandom(alphabet, size, random)
- let nanoid = (size = 21) => {
- let id = ''
- let bytes = crypto.getRandomValues(new Uint8Array(size))
- // 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.
- let byte = bytes[size] & 63
- if (byte < 36) {
- // `0-9a-z`
- id += byte.toString(36)
- } else if (byte < 62) {
- // `A-Z`
- id += (byte - 26).toString(36).toUpperCase()
- } else if (byte < 63) {
- id += '_'
- } else {
- id += '-'
- }
- }
- return id
- }
- export { nanoid, customAlphabet, customRandom, urlAlphabet, random }
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