random.ts

import crypto from 'crypto';

export function getRandomBytes(numBytes: number): Promise<Buffer> {
  return new Promise((resolve, reject) => {
    crypto.randomBytes(numBytes, (error, result) => {
      error ? reject(error) : resolve(result);
    });
  });
}

export async function getRandomBase36(numChars: number): Promise<string> {
  let result = '';
  while (result.length < numChars) {
    let num = Math.pow(256, 2);
    while (num > Math.pow(36, 3)) {
      let [a, b] = await getRandomBytes(2);
      num = a * 256 + b;
    }
    result += num.toString(36);
  }
  return result.slice(0, numChars);
}

export async function getRandomBase64(
  numChars: number,
  urlSafe = false,
): Promise<string> {
  let result = '';
  while (result.length < numChars) {
    let buffer = await getRandomBytes(3);
    result += buffer.toString('base64');
  }
  result = result.slice(0, numChars);
  if (urlSafe) {
    result = result.split('+').join('-');
    result = result.split('/').join('_');
  }
  return result;
}