random.js

var baseRandom = require('./_baseRandom'),
    isIterateeCall = require('./_isIterateeCall'),
    toFinite = require('./toFinite');

/** Built-in method references without a dependency on `root`. */
var freeParseFloat = parseFloat;

/* Built-in method references for those with the same name as other `lodash` methods. */
var nativeMin = Math.min,
    nativeRandom = Math.random;

/**
 * Produces a random number between the inclusive `lower` and `upper` bounds.
 * If only one argument is provided a number between `0` and the given number
 * is returned. If `floating` is `true`, or either `lower` or `upper` are
 * floats, a floating-point number is returned instead of an integer.
 *
 * **Note:** JavaScript follows the IEEE-754 standard for resolving
 * floating-point values which can produce unexpected results.
 *
 * @static
 * @memberOf _
 * @since 0.7.0
 * @category Number
 * @param {number} [lower=0] The lower bound.
 * @param {number} [upper=1] The upper bound.
 * @param {boolean} [floating] Specify returning a floating-point number.
 * @returns {number} Returns the random number.
 * @example
 *
 * _.random(0, 5);
 * // => an integer between 0 and 5
 *
 * _.random(5);
 * // => also an integer between 0 and 5
 *
 * _.random(5, true);
 * // => a floating-point number between 0 and 5
 *
 * _.random(1.2, 5.2);
 * // => a floating-point number between 1.2 and 5.2
 */
function random(lower, upper, floating) {
  if (floating && typeof floating != 'boolean' && isIterateeCall(lower, upper, floating)) {
    upper = floating = undefined;
  }
  if (floating === undefined) {
    if (typeof upper == 'boolean') {
      floating = upper;
      upper = undefined;
    }
    else if (typeof lower == 'boolean') {
      floating = lower;
      lower = undefined;
    }
  }
  if (lower === undefined && upper === undefined) {
    lower = 0;
    upper = 1;
  }
  else {
    lower = toFinite(lower);
    if (upper === undefined) {
      upper = lower;
      lower = 0;
    } else {
      upper = toFinite(upper);
    }
  }
  if (lower > upper) {
    var temp = lower;
    lower = upper;
    upper = temp;
  }
  if (floating || lower % 1 || upper % 1) {
    var rand = nativeRandom();
    return nativeMin(lower + (rand * (upper - lower + freeParseFloat('1e-' + ((rand + '').length - 1)))), upper);
  }
  return baseRandom(lower, upper);
}

module.exports = random;