simple-squiggle

A restricted subset of Squiggle
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browser.js (1577B)

      1 'use strict'
      2 
      3 // limit of Crypto.getRandomValues()
      4 // https://developer.mozilla.org/en-US/docs/Web/API/Crypto/getRandomValues
      5 var MAX_BYTES = 65536
      6 
      7 // Node supports requesting up to this number of bytes
      8 // https://github.com/nodejs/node/blob/master/lib/internal/crypto/random.js#L48
      9 var MAX_UINT32 = 4294967295
     10 
     11 function oldBrowser () {
     12   throw new Error('Secure random number generation is not supported by this browser.\nUse Chrome, Firefox or Internet Explorer 11')
     13 }
     14 
     15 var Buffer = require('safe-buffer').Buffer
     16 var crypto = global.crypto || global.msCrypto
     17 
     18 if (crypto && crypto.getRandomValues) {
     19   module.exports = randomBytes
     20 } else {
     21   module.exports = oldBrowser
     22 }
     23 
     24 function randomBytes (size, cb) {
     25   // phantomjs needs to throw
     26   if (size > MAX_UINT32) throw new RangeError('requested too many random bytes')
     27 
     28   var bytes = Buffer.allocUnsafe(size)
     29 
     30   if (size > 0) {  // getRandomValues fails on IE if size == 0
     31     if (size > MAX_BYTES) { // this is the max bytes crypto.getRandomValues
     32       // can do at once see https://developer.mozilla.org/en-US/docs/Web/API/window.crypto.getRandomValues
     33       for (var generated = 0; generated < size; generated += MAX_BYTES) {
     34         // buffer.slice automatically checks if the end is past the end of
     35         // the buffer so we don't have to here
     36         crypto.getRandomValues(bytes.slice(generated, generated + MAX_BYTES))
     37       }
     38     } else {
     39       crypto.getRandomValues(bytes)
     40     }
     41   }
     42 
     43   if (typeof cb === 'function') {
     44     return process.nextTick(function () {
     45       cb(null, bytes)
     46     })
     47   }
     48 
     49   return bytes
     50 }