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random.js
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random.js
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/**
* Isomorphic module for true random numbers / buffers / uuids.
*
* Attention: falls back to Math.random if the browser does not support crypto.
*
* @module random
*/
import * as math from './math.js'
import { cryptoRandomBuffer } from './isomorphic.js'
export const rand = Math.random
/* istanbul ignore next */
export const uint32 = () => new Uint32Array(cryptoRandomBuffer(4))[0]
/**
* @template T
* @param {Array<T>} arr
* @return {T}
*/
export const oneOf = arr => arr[math.floor(rand() * arr.length)]
// @ts-ignore
const uuidv4Template = [1e7] + -1e3 + -4e3 + -8e3 + -1e11
export const uuidv4 = () => uuidv4Template.replace(/[018]/g, /** @param {number} c */ c =>
(c ^ uint32() & 15 >> c / 4).toString(16)
)