rando.js

const crypto = require("crypto");

function gen(
  rand = Math.random,
  n = 10,
  alphabet = "abcdefghijklmnopqrstuvwxyz"
) {
  let p = "";
  for (var i = 0; i < n; i++)
    p += alphabet[Math.floor(rand() * alphabet.length)];
  return p;
}

function printCharCounts(d) {
  const counter = {};
  for (var i = 0; i < d.length; i++) {
    counter[d[i]] = (counter[d[i]] || 0) + 1;
  }
  Object.keys(counter)
    .sort()
    .forEach(key => {
      console.log(`${key}\t${counter[key]}`);
    });
}

let randomBuf = [];

const cryptoBufferRand = () => {
  if (!randomBuf.length) {
    randomBuf = randomBuf.concat(Array.from(crypto.randomBytes(512)));
  }
  return randomBuf.shift() / 255;
};

const cryptoRand = () => crypto.randomBytes(1)[0] / 255;

printCharCounts(gen(Math.random, 100000));