lodash/collection/sample.js

import baseRandom from '../internal/baseRandom';
import isIterateeCall from '../internal/isIterateeCall';
import shuffle from './shuffle';
import toIterable from '../internal/toIterable';

/* Native method references for those with the same name as other `lodash` methods. */
var nativeMin = Math.min;

/**
 * Gets a random element or `n` random elements from a collection.
 *
 * @static
 * @memberOf _
 * @category Collection
 * @param {Array|Object|string} collection The collection to sample.
 * @param {number} [n] The number of elements to sample.
 * @param- {Object} [guard] Enables use as a callback for functions like `_.map`.
 * @returns {*} Returns the random sample(s).
 * @example
 *
 * _.sample([1, 2, 3, 4]);
 * // => 2
 *
 * _.sample([1, 2, 3, 4], 2);
 * // => [3, 1]
 */
function sample(collection, n, guard) {
  if (guard ? isIterateeCall(collection, n, guard) : n == null) {
    collection = toIterable(collection);
    var length = collection.length;
    return length > 0 ? collection[baseRandom(0, length - 1)] : undefined;
  }
  var result = shuffle(collection);
  result.length = nativeMin(n < 0 ? 0 : (+n || 0), result.length);
  return result;
}

export default sample;