Generates a cryptographically secure number [0-1) as an alternative to Math.random()

secureRandom.js

// Generates a cryptographically secure number [0-1)
// as an alternative to Math.random()
//
// source: http://stackoverflow.com/a/13694869/1319878
function secureRandom() {
  var arr = new Uint32Array(2);
  crypto.getRandomValues(arr);

  // keep all 32 bits of the the first, top 20 of the second for 52 random bits
  var mantissa = (arr[0] * Math.pow(2,20)) + (arr[1] >>> 12)

  // shift all 52 bits to the right of the decimal point
  return mantissa * Math.pow(2,-52);
}