38 lines
923 B
JavaScript
38 lines
923 B
JavaScript
/**
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* Isomorphic module for true random numbers / buffers / uuids.
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*
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* Attention: falls back to Math.random if the browser does not support crypto.
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*
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* @module random
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*/
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import * as math from './math.js'
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import * as binary from './binary.js'
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import { getRandomValues } from 'lib0/webcrypto'
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export const rand = Math.random
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export const uint32 = () => getRandomValues(new Uint32Array(1))[0]
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export const uint53 = () => {
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const arr = getRandomValues(new Uint32Array(8))
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return (arr[0] & binary.BITS21) * (binary.BITS32 + 1) + (arr[1] >>> 0)
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}
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/**
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* @template T
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* @param {Array<T>} arr
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* @return {T}
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*/
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export const oneOf = arr => arr[math.floor(rand() * arr.length)]
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// @ts-ignore
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const uuidv4Template = [1e7] + -1e3 + -4e3 + -8e3 + -1e11
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/**
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* @return {string}
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*/
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export const uuidv4 = () => uuidv4Template.replace(/[018]/g, /** @param {number} c */ c =>
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(c ^ uint32() & 15 >> c / 4).toString(16)
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)
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