Generates a cryptographically secure pseudorandom number from 0 to 255. Written in typescript (javascript)

randomInt.ts

//MIT license.
/**
 * @file Considering that using PRNG is not secure,
 * this function provides a cryptographically secure random integer (CSPRNG).
 */
import { randomBytes } from 'crypto';

/**
 * Generates a cryptographically secure pseudorandom number from 0 to 255,
 * as specified by (`min`,`max`)
 * @param {number} min A minimum expected number ─ *default: `0`*
 * @param {number} max A maximum expected number ─ *default: `255`*
 */
export default function randomUint8(min = 0, max = 255): number {
  //parameters check
  if (min === max) {
    return max;
  }
  if (min > max) {
    const minAux = min; //auxiliary const
    min = max;
    max = minAux;
  }
  if (max > 255) {
    max = 255;
  }

  const randomByte: number = randomBytes(1)[0];

  if(min === 0 && max === 255){
    return randomByte;
  }

  const range = max - min + 1;
  const max_range = 256;

  if (randomByte >= Math.floor(max_range / range) * range) {
    return randomUint8(min, max);
  }

  return min + (randomByte % range);
}

Otra versión en Javascript

//MIT license.
/**
 * @file Considering that using PRNG is not secure,
 * this function provides a cryptographically secure random integer (CSPRNG).
 */
import { randomBytes } from "crypto";

/**
 * Generates a cryptographically secure pseudorandom number from 0 to 255,
 * as specified by (`min`,`max`)
 * @param {number} min A minimum expected number ─ *default: `0`*
 * @param {number} max A maximum expected number ─ *default: `255`*
 * @returns {number}
 */
export default function random_uint8(min = 0, max = 255) {
    //parameters check
    if (min === max) return max;
    if (min > max) {
        const minAux = min; //auxiliary const
        min = max;
        max = minAux;
    }
    if (max > 255) max = 255;

    const randomByte = randomBytes(1)[0];

    if(min === 0 && max === 255) return randomByte;

    const range = max - min + 1;
    const max_range = 256;

    if (randomByte >= Math.floor(max_range / range) * range) 
        return random_uint8(min, max);

    return min + (randomByte % range);
}