randomize-any/dist/index.browser.cjs-legacy.cjs

A secure randomization utility library that provides various randomization functions, supporting both browser and Node.js environments.

'use strict';

Object.defineProperty(exports, '__esModule', { value: true });

var _mapInstanceProperty = require('@babel/runtime-corejs3/core-js-stable/instance/map');
var _reduceInstanceProperty = require('@babel/runtime-corejs3/core-js-stable/instance/reduce');

function _interopDefaultLegacy (e) { return e && typeof e === 'object' && 'default' in e ? e : { 'default': e }; }

var _mapInstanceProperty__default = /*#__PURE__*/_interopDefaultLegacy(_mapInstanceProperty);
var _reduceInstanceProperty__default = /*#__PURE__*/_interopDefaultLegacy(_reduceInstanceProperty);

/**
 * Randomize an element from an array
 * @param list array
 * @returns randomized element
 */
function randomizeAny(list) {
  var targetIndex = getSecureWeightedRandom(_mapInstanceProperty__default['default'](list).call(list, () => 1));
  return list[targetIndex];
}

/**
 * Randomize an integer
 * @param min minimum value
 * @param max maximum value
 * @returns randomized integer
 */
function randomizeInteger(min, max) {
  var list = generateArray(min, max);
  return randomizeAny(list);
}

/**
 * Randomize a float number
 * @param min minimum value
 * @param max maximum value
 * @returns randomized float number
 */
function randomizeFloat(min, max) {
  var list = generateArray(min, max, 0.01);
  return randomizeAny(list);
}

/**
 * Get a secure weighted random number
 * @param weights weight array
 * @returns randomized index
 */
function getSecureWeightedRandom(weights) {
  var sum = _reduceInstanceProperty__default['default'](weights).call(weights, (acc, val) => acc + val, 0); // Calculate total weight

  // Generate a secure random number (range 0 ~ sum-1)
  var array = new Uint32Array(1);
  window.crypto.getRandomValues(array);
  var rand = array[0] / (0xFFFFFFFF + 1) * sum; // Normalize to [0, sum)

  // Iterate through weight array to find corresponding random index
  var cumulative = 0;
  for (var i = 0; i < weights.length; i++) {
    cumulative += weights[i];
    if (rand < cumulative) {
      return i;
    }
  }
  return getWeightedRandom(weights);
}

/**
 * Get a weighted random number
 * @param weights weight array
 * @returns randomized index
 */
function getWeightedRandom(weights) {
  var total = _reduceInstanceProperty__default['default'](weights).call(weights, (acc, curr) => acc + curr, 0);
  var random = Math.random() * total;
  var sum = 0;
  for (var i = 0; i < weights.length; i++) {
    sum += weights[i];
    if (random < sum) {
      return i;
    }
  }
}

/**
 * Generate an array
 * @param min minimum value
 * @param max maximum value
 * @param step step size
 * @returns array
 */
function generateArray(min, max) {
  var step = arguments.length > 2 && arguments[2] !== undefined ? arguments[2] : 1;
  var array = [];
  for (var i = min; i <= max; i += step) {
    array.push(i);
  }
  return array;
}

exports.getSecureWeightedRandom = getSecureWeightedRandom;
exports.randomizeAny = randomizeAny;
exports.randomizeFloat = randomizeFloat;
exports.randomizeInteger = randomizeInteger;